feat: playgrounds in JS VSCODE-372 (#482)

* feat: replace mongodb language with javascript in playgrounds

* feat: use js grammar only

* feat: save playgrounds as mongodb ext

* docs: add comment about read-only root

* refactor: clean up

* refactor: better handling new files

* refactor: drop fragment

* feat: add mongodb grammar injection

* refactor: restore update-grammar script

* docs: update contributing page

* refactor: update-grammar

* feat: update mongodb injection grammar

* test: update for playgrounds in js

* refactor: reformat

* refactor: restore snippets

* refactor: clean up

* build: bump vscode engine

* build: clean up dependencies

* refactor: reforamt

* build: try with prev npm

* build: try old deps

* refactor: reformat

* test: use activeTextEditor from the playground controller

* refactor: os homedir

* refactor: clean up

* refactor: address pr comments

* test: try bigger timeout

* test: less playground documents open

* test: clean up

* test: assert.strictEqual

* test: mock text flaky text document

Author: alenakhineika

CONTRIBUTING.md

@@ -37,13 +37,12 @@ npm run watch
 
 #### Code Tour
 
-- `out` compiled extension code
+- `out` Compiled extension code
 - `images` Icons, logos, etc.
-- `snippets` [Bundled MongoDB Snippets][snippet guide]
-- `syntaxes` [Syntax highlighting for `.mongodb` files][syntax guide]
-- `src`
-  - `test/suite` where tests live with files names `*.test.ts`
-- `scripts` project helper scripts
+- `snippets` Bundled MongoDB Snippets
+- `syntaxes` [Syntax highlighting](https://code.visualstudio.com/api/language-extensions/syntax-highlight-guide#injection-grammars) for MongoDB keywords
+- `src/test/suite` Where tests live with '`*.test.ts`' files names
+- `scripts` Project helper scripts
 
 ## Releases