* Add dotenv support
This adds basic language support for the dotenv language. This includes
syntax highlighting and a language configuration file.
The dotenv language is applied to files with the `.env` extension, files
named `.env`, `.flaskenv`, or `user-dirs.dirs`, and file names starting
with `.env.`.
The grammar is downloaded from https://github.com/dotenv-org/dotenv-vscode.
Closes#267333
* Add tests
* Remove ini and shellscript language conflicting with dotenv
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Co-authored-by: Alex Ross <38270282+alexr00@users.noreply.github.com>
