Add support for XQuery

[KingDarBoja]

Fixes #1888

Changes proposed:

• Add
• Delete
• Fix
• Prepare

Note: I'm using temporary the xml icon for this one.

[JimiC]

1. We already have an icon with icon: 'xml'.
2. The icon is missing from the commit.
3. All the extensions added are already supported by the languageid (https://github.com/DotJoshJohnson/vscode-xml/blob/master/package.json#L212).

[codecov]

Codecov Report

Merging #2039 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #2039   +/-   ##
======================================
  Coverage     100%    100%           
======================================
  Files          78      78           
  Lines        5948    5948           
  Branches      138     138           
======================================
  Hits         5948    5948

Impacted Files	Coverage Δ
src/iconsManifest/supportedExtensions.ts	100% <ø> (ø)	⬆️
src/iconsManifest/languages.ts	100% <ø> (ø)	⬆️

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[JimiC]

That said. We have to add a test to avoid duplicate declarations.

[JimiC]

I prefer to use a different icon for xquery than the plainxml one. My proposal is the xml icon with a question mark as the overlaying icon.

[JimiC]

Much better. I take it you tested it out for dark and light themes.