Fixes #23484

Fixes #23621

Part of #25740

To support TS Server plugins for languages like angular, we will allow extensions to register new langauges for TypeScript to watch. The angular language for example would want ng-html files to also be uploaded to TypeScript for checking

The current language definitions all define both a set of language modes they support and a set of file extensions. The file extension part is unnessiary and may be incorrect depending on how a user sets up their `file.associations` in the workspace. This change removes the extensions part so that we always make use of the language mode

This reverts commit b9988fed.

fixes #8851

This reverts commit f3ffc2ed.

Lua syntax extension is missing 'goto' keyword

Correct LC_ALL.  Resolves #26227

Fixes #26406

**Bug**
If there is an active selection, the on Enter rules may use the wrong language mode which results in the incorrect `afterEnterText`. See #26406 for an example of this case

**Fix**
Use language mode from the selection and  correctly compute offset when grabbing `afterEnterText`