chore: remove examples/externalPlugins.js and pluginLoader.ts, update imports to .js

Deleted `examples/externalPlugins.js` and `pluginLoader.ts` as they are no longer used. Updated all `.ts` imports to `.js` across the codebase. Added `MemberOf` to `VerbType` and filtered disabled augmentations in `executeAugmentationPipeline`. Updated documentation to reflect new augmentation registration process. Removed deprecated `allowImportingTsExtensions` from `tsconfig.json`.

src/types/augmentations.ts

@@ -35,6 +35,8 @@ export interface IAugmentation {
   readonly name: string
   /** A human-readable description of the augmentation's purpose */
   readonly description: string
+  /** Whether this augmentation is enabled */
+  enabled: boolean
 
   /**
    * Initializes the augmentation. This method is called when Brainy starts up.