Support ktlint 0.50.0 and drop support for 0.47.0

[magneticflux-]

Closes #1741

Please DO NOT FORCE PUSH. Don't worry about messy history, it's easier to do code review if we can tell what happened after the review, and force pushing breaks that.

Please make sure that your PR allows edits from maintainers. Sometimes its faster for us to just fix something than it is to describe how to fix it.

After creating the PR, please add a commit that adds a bullet-point under the [Unreleased] section of CHANGES.md, plugin-gradle/CHANGES.md, and plugin-maven/CHANGES.md which includes:

• a summary of the change
• either
  • a link to the issue you are resolving (for small changes)
  • a link to the PR you just created (for big changes likely to have discussion)

If your change only affects a build plugin, and not the lib, then you only need to update the plugin-foo/CHANGES.md for that plugin.

If your change affects lib in an end-user-visible way (fixing a bug, updating a version) then you need to update CHANGES.md for both the lib and all build plugins. Users of a build plugin shouldn't have to refer to lib to see changes that affect them.

This makes it easier for the maintainers to quickly release your changes :)

---

Additional notes for discussion:

• KtLint 0.50.0 introduces a new default rule wrapping that changes the formatting of resources/kotlin/ktlint/basic.dirty. I created basic-old.clean for KtLint < 0.50.0 and changed basic.clean to wrap the semicolon-separated lines.
• KtLintCompat0Dot50Dot0Adapter constructs a KtLintRuleEngine with the default value of true for enableKotlinCompilerExtensionPoint. We may want this to be user-configurable to help people debug their custom rule providers. More info here: Remove usages of ExtensionsArea.registerExtensionPoint(java.lang.String, java.lang.String, com.intellij.openapi.extensions.ExtensionPoint.Kind) pinterest/ktlint#1981
• EditorConfigDefaults.Companion.load supports adding custom property types to parse from the .editorconfig, in addition to the defaults. Another potential location for user-configuration.

[magneticflux-]

An additional note:
Since this drops support for KtLint 0.47.0, all supported releases of KtLint use the ktlint_experimental EditorConfig property instead of a special parameter (0.48.0 changelog). Should we drop the boolean useExperimental parameter from KtLintCompatAdapter and rely solely on ktlint_experimental? This would clean up some warning code in each compat adapter: https://github.com/diffplug/spotless/blob/3bafa6a28e4c3f1f982f06f652b793758f443169/lib/src/compatKtLint0Dot50Dot0/java/com/diffplug/spotless/glue/ktlint/compat/KtLintCompat0Dot50Dot0Adapter.java#L96C1-L104

[nedtwigg]

Sorry for the slow review, this is great!

Should we drop the boolean useExperimental parameter from KtLintCompatAdapter and rely solely on ktlint_experimental? This would clean up some warning code in each compat adapter:

That would be fantastic, thanks! I'll merge and release as soon as that is complete.

[magneticflux-]

Expected impact of the removal of useExperimental is minimal.

• ~105 usages with
• ~5100 usages without

[magneticflux-]

The NPM eslintStyleguideXo() test failure seems unrelated.

Error: ROR] Step 'eslint-format' found problem in 'src/main/typescript/test.ts':
  > Unexpected response status code at /eslint/format [HTTP 500] -- (Error while formatting: Error: --config#overrides[0] » eslint-config-xo-typescript:
  > 	Configuration for rule "@typescript-eslint/no-restricted-imports" is invalid:
  > 	Value ["error","domain","freelist","smalloc","punycode","sys","querystring","colors"] should be string.
  > 	Value ["error","domain","freelist","smalloc","punycode","sys","querystring","colors"] should be object.
  > 	Value ["error","domain","freelist","smalloc","punycode","sys","querystring","colors"] should match some schema in anyOf.
  > 	Value ["error","domain","freelist","smalloc","punycode","sys","querystring","colors"] should be object.
  > 	Value [["error","domain","freelist","smalloc","punycode","sys","querystring","colors"]] should match some schema in anyOf.
  > )
  > com.diffplug.spotless.npm.SimpleRestClient$SimpleRestResponseException: Unexpected response status code at /eslint/format [HTTP 500] -- (Error while formatting: Error: --config#overrides[0] » eslint-config-xo-typescript:
  > 	Configuration for rule "@typescript-eslint/no-restricted-imports" is invalid:
  > 	Value ["error","domain","freelist","smalloc","punycode","sys","querystring","colors"] should be string.
  > 	Value ["error","domain","freelist","smalloc","punycode","sys","querystring","colors"] should be object.
  > 	Value ["error","domain","freelist","smalloc","punycode","sys","querystring","colors"] should match some schema in anyOf.
  > 	Value ["error","domain","freelist","smalloc","punycode","sys","querystring","colors"] should be object.
  > 	Value [["error","domain","freelist","smalloc","punycode","sys","querystring","colors"]] should match some schema in anyOf.
  > )

[nedtwigg]

Released in plugin-gradle 6.20.0 and plugin-maven 2.38.0.