Update .gitattributes and .gitignore

* Make the ordering of the file names more consistent (directories first, files after).
* Update the list of files to be export-ignored.

Author: jrfnl

.gitattributes

@@ -13,6 +13,7 @@ scripts/                export-ignore
 .markdownlint-cli2.yaml export-ignore
 .remarkignore           export-ignore
 .remarkrc               export-ignore
+.shellcheckrc           export-ignore
 .yamllint.yml           export-ignore
 phpcs.xml.dist          export-ignore
 phpstan.neon.dist       export-ignore

.gitignore

@@ -1,12 +1,12 @@
+.idea/*
+build/
+lib/
+node_modules/
+vendor/
+/.phpunit.result.cache
 /CodeSniffer.conf
+/composer.lock
 /phpcs.xml
+/phpstan.neon
 /phpunit.xml
-.phpunit.result.cache
-/build/
-.idea/*
-/vendor/
-composer.lock
-phpstan.neon
-/node_modules/
 /tests/EndToEnd/Fixtures/*.fixed
-/lib/