Implement pgxn_meta CLI

Keep it simple right now, mimicking [validate_pgxn_meta], although the
`--man` option currently doesn't do much. Use lexopt for argument
parsing, since it's super simple like this use case.

Avoid [std::process::exit] and set a boolean to return
[std::process::ExitCode] when the app should exit without processing a
file. This makes it easier to test things, since the functions to print
the usage statement or version don't exit.

Include tests that cover every bit of functionality, including the
`main()` function. Add `corpus/invalid.json` to properly test validation
failure. Try to improve the coveralls formatting.

  [validate_pgxn_meta]: https://metacpan.org/pod/validate_pgxn_meta
  [std::process::exit]: https://doc.rust-lang.org/stable/std/process/fn.exit.html
  [std::process::ExitCode]: https://doc.rust-lang.org/stable/std/process/struct.ExitCode.html

Author: theory

.ci/test-cover

@@ -23,9 +23,8 @@ grcov "${DESTDIR}" \
     -s . \
     --branch \
     -o "${DESTDIR}" \
-    --output-types html,cobertura
-
-xmllint --xpath "concat('Coverage: ', 100 * string(//coverage/@line-rate), '%')" "${DESTDIR}/cobertura.xml"
+    --token 5DOLLPIHEO \
+    --output-types html,coveralls
 
 if [ "$(uname -o)" = "Darwin" ] && [ -z "$CI" ]; then
 	open "${DESTDIR}/html/index.html"

.github/workflows/test-and-lint.yml

@@ -33,13 +33,11 @@ jobs:
         uses: dtolnay/rust-toolchain@stable
       - name: Run pre-commit
         uses: pre-commit/[email protected]
-      - name: Install dependencies
-        run: sudo apt-get install -y libxml2-utils
       - name: Generate Coverage
         run: make cover RUST_BACKTRACE=1
       - name: Publish Coverage
         uses: codecov/codecov-action@v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           slug: pgxn/meta
-          files: target/cover/cobertura.xml
+          files: target/cover/coveralls

Cargo.lock

@@ -14,6 +14,7 @@ exclude = [ ".github", ".gitattributes", "target", ".vscode", ".gitignore" ]
 
 [dependencies]
 boon = "0.6"
+lexopt = "0.3.0"
 relative-path = "1.9.3"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1.0"

Cargo.toml

@@ -0,0 +1,20 @@
+{
+  "name": "pair",
+  "abstract": "A key/value pair data type",
+  "maintainers": [
+    {
+      "name": "David E. Wheeler",
+      "email": "[email protected]"
+    }
+  ],
+  "license": "PostgreSQL",
+  "contents": {
+    "extensions": {
+      "pair": {
+        "sql": "sql/pair.sql",
+        "control": "pair.control"
+      }
+    }
+  },
+  "meta-spec": { "version": "2.0.0" }
+}