[eslint-import-resolver] support mapping plugins to directories (#17667)

* [eslint-import-resolver] support mapping plugins to directories

* use shorthand syntax

packages/kbn-eslint-import-resolver-kibana/README.md

@@ -29,6 +29,7 @@ Property | Default | Description
 rootPackageName | `null` | The `"name"` property of the root `package.json` file. If your project has multiple `package.json` files then specify this setting to tell the resolver which `package.json` file sits at the root of your project.
 pluginPaths | `[]` if `rootPackageName` is set, otherwise `[.]` | Array of relative paths which contain a Kibana plugin. Plugins must contain a `package.json` file to be valid.
 pluginDirs | `[]` | Array of relative paths pointing to directories which contain Kibana plugins. Plugins must contain a `package.json` file to be valid.
+pluginMap | `{}` | A map of plugin ids to relative paths, explicitly pointing to the location where Kibana should map `plugin/{pluginId}` import statements. Directories do not need to contain a `package.json` file to work.
 
 ## Settings Usage
 To specify additional config add a `:` after the resolver name and specify the argument as key-value pairs:
@@ -51,6 +52,12 @@ settings:
       # that directory and we will look for plugins there
       pluginDirs:
         - ./kibana-plugins
+
+      # if you have some other special configuration supply a map of plugin
+      # ids to the directory containing their code
+      pluginMap:
+        plugin1: plugins/plugin1
+        plugin2: plugins/plugin2
 ```
 
 See [the resolvers docs](https://github.com/benmosher/eslint-plugin-import#resolvers) or the [resolver spec](https://github.com/benmosher/eslint-plugin-import/blob/master/resolvers/README.md#resolvesource-file-config---found-boolean-path-string-) for more details.

packages/kbn-eslint-import-resolver-kibana/lib/get_plugins.js

@@ -23,13 +23,24 @@ module.exports = function getPlugins(config, kibanaPath, projectRoot) {
     ...pluginPaths.map(path => resolve(path, 'package.json')),
   ];
 
-  return glob.sync(globPatterns).map(pkgJsonPath => {
-    const path = dirname(pkgJsonPath);
-    const pkg = require(pkgJsonPath);
+  const pluginsFromMap = Object.keys(config.pluginMap || {}).map(name => {
+    const directory = resolveToRoot(config.pluginMap[name]);
     return {
-      name: pkg.name,
-      directory: path,
-      publicDirectory: resolve(path, 'public'),
+      name,
+      directory,
+      publicDirectory: resolve(directory, 'public'),
     };
   });
+
+  return pluginsFromMap.concat(
+    glob.sync(globPatterns).map(pkgJsonPath => {
+      const path = dirname(pkgJsonPath);
+      const pkg = require(pkgJsonPath);
+      return {
+        name: pkg.name,
+        directory: path,
+        publicDirectory: resolve(path, 'public'),
+      };
+    })
+  );
 };