Fix a concurrent map write with the --inject: feature (#878)

This release fixes an issue where esbuild could potentially crash sometimes with a concurrent map write when using injected files and entry points that were neither relative nor absolute paths. This was an edge case where esbuild's low-level file subsystem was being used without being behind a mutex lock. This regression was likely introduced in version 0.8.21. The cause of the crash has been fixed.

Provide kind to onResolve plugins (#879)

Plugins that add onResolve callbacks now have access to the kind parameter which tells you what kind of import is being resolved. It will be one of the following values:

• "entry-point" in JS (api.ResolveEntryPoint in Go)

  An entry point provided by the user

• "import-statement" in JS (api.ResolveJSImportStatement in Go)

  A JavaScript import or export statement

• "require-call" in JS (api.ResolveJSRequireCall in Go)

  A JavaScript call to require(...) with a string argument

• "dynamic-import" in JS (api.ResolveJSDynamicImport in Go)

  A JavaScript import(...) expression with a string argument

• "require-resolve" in JS (api.ResolveJSRequireResolve in Go)

  A JavaScript call to require.resolve(...) with a string argument

• "import-rule" in JS (api.ResolveCSSImportRule in Go)

  A CSS [@import](https://github.com/import) rule

• "url-token" in JS (api.ResolveCSSURLToken in Go)

  A CSS url(...) token

These values are pretty much identical to the kind field in the JSON metadata file.