feat: added setting up swift environment

- support macOS, linux completely
- added limited support of Windows
- added swift development versions support
- added unit, integration and feature tests
- added toolchain snapshot metadata auto-sync with swift.org

Author: soumyamahunt

.eslintignore

@@ -0,0 +1,4 @@
+dist/
+lib/
+node_modules/
+swiftorg/

.eslintrc.json

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+{
+  "plugins": ["jest", "@typescript-eslint"],
+  "extends": ["plugin:github/recommended"],
+  "parser": "@typescript-eslint/parser",
+  "parserOptions": {
+    "ecmaVersion": 9,
+    "sourceType": "module",
+    "project": "./tsconfig.json"
+  },
+  "rules": {
+    "i18n-text/no-en": "off",
+    "eslint-comments/no-use": "off",
+    "import/no-namespace": "off",
+    "no-unused-vars": "off",
+    "@typescript-eslint/no-unused-vars": "error",
+    "@typescript-eslint/explicit-member-accessibility": [
+      "error",
+      {"accessibility": "no-public"}
+    ],
+    "@typescript-eslint/no-require-imports": "error",
+    "@typescript-eslint/array-type": "error",
+    "@typescript-eslint/await-thenable": "error",
+    "@typescript-eslint/ban-ts-comment": "error",
+    "camelcase": "off",
+    "@typescript-eslint/consistent-type-assertions": "error",
+    "@typescript-eslint/func-call-spacing": ["error", "never"],
+    "@typescript-eslint/no-array-constructor": "error",
+    "@typescript-eslint/no-empty-interface": "error",
+    "@typescript-eslint/no-explicit-any": "error",
+    "@typescript-eslint/no-extraneous-class": "error",
+    "@typescript-eslint/no-for-in-array": "error",
+    "@typescript-eslint/no-inferrable-types": "error",
+    "@typescript-eslint/no-misused-new": "error",
+    "@typescript-eslint/no-non-null-assertion": "warn",
+    "@typescript-eslint/no-unnecessary-qualifier": "error",
+    "@typescript-eslint/no-unnecessary-type-assertion": "error",
+    "@typescript-eslint/no-useless-constructor": "error",
+    "@typescript-eslint/no-var-requires": "error",
+    "@typescript-eslint/prefer-for-of": "warn",
+    "@typescript-eslint/prefer-function-type": "warn",
+    "@typescript-eslint/prefer-includes": "error",
+    "@typescript-eslint/prefer-string-starts-ends-with": "error",
+    "@typescript-eslint/promise-function-async": "error",
+    "@typescript-eslint/require-array-sort-compare": "error",
+    "@typescript-eslint/restrict-plus-operands": "error",
+    "semi": "off",
+    "@typescript-eslint/semi": ["error", "never"],
+    "@typescript-eslint/type-annotation-spacing": "error",
+    "@typescript-eslint/unbound-method": "error"
+  },
+  "env": {
+    "node": true,
+    "es6": true,
+    "jest/globals": true
+  }
+}

.gitattributes

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+dist/** -diff linguist-generated=true

.github/changelog/config.js

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+'use strict'
+const config = require('conventional-changelog-conventionalcommits');
+
+module.exports = config({
+  types: [
+    {type: 'feat', section: '🚀 Features'},
+    {type: 'fix', section: '🐛 Fixes'},
+    {type: 'perf', section: '🐎 Performance Improvements'},
+    {type: 'revert', section: '⏪ Reverts'},
+    {type: 'build', section: '🛠 Build System'},
+    {type: 'deps', section: '🛠 Dependency'},
+    {type: 'refactor', section: '🔥 Refactorings'},
+    {type: 'doc', section: '📚 Documentation'},
+    {type: 'docs', section: '📚 Documentation'},
+    {type: 'style', section: '💄 Styles'},
+    {type: 'test', section: '✅ Tests'},
+    {type: 'ci', hidden: true},
+    {type: 'wip', hidden: true},
+    {type: 'chore', hidden: true}
+  ]
+});

.github/changelog/pre_changelog_hook.js

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+'use strict'
+const semver = require('semver');
+const core = require('@actions/core');
+
+exports.preVersionGeneration = (version) => {
+  const {VERSION} = process.env;
+  core.info(`Computed version bump: ${version}`);
+
+  const newVersion = semver.valid(VERSION);
+  if (newVersion) {
+    version = newVersion;
+    core.info(`Using provided version: ${version}`);
+  }
+  return version;
+};
+
+exports.preTagGeneration = (tag) => {};

.github/changelog/pre_commit_hook.js

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+'use strict'
+const core = require('@actions/core');
+const {exec, getExecOutput} = require('@actions/exec');
+
+exports.preCommit = async (props) => {
+  const gitOptions = {cwd: 'swiftorg'};
+  const {stdout} = await getExecOutput('git', ['rev-parse', '--verify', 'HEAD'], gitOptions);
+  const swiftorg = stdout.trim();
+  core.info(`Updating swiftorg to "${swiftorg}"`);
+  await exec('npm', ['pkg', 'set', `swiftorg=${swiftorg}`]);
+
+  core.startGroup(`Bundling`);
+  await exec('npm install');
+  await exec('npm run package');
+  core.endGroup();
+};

.github/dependabot.yml

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+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: monthly
+    commit-message:
+      prefix: 'ci(Deps): '
+
+  - package-ecosystem: gitsubmodule
+    directory: /
+    schedule:
+      interval: daily
+    commit-message:
+      prefix: 'build: '
+
+  - package-ecosystem: npm
+    directory: /
+    schedule:
+      interval: monthly
+    commit-message:
+      prefix: 'deps: '
+      prefix-development: 'chore: '