Explore 'vscode-css-languageservice' as default parser for all files

[mrmlnc]

Now the scss-symbols-parser package is outdated and has a some bugs. For example, this package does not support @use and cannot parse correctly the following content from Bootstrap:

$grid-breakpoints: (
  xs: 0,
  sm: 576px,
  md: 768px,
  lg: 992px,
  xl: 1200px
) !default;

@include _assert-ascending($grid-breakpoints, "$grid-breakpoints");
@include _assert-starts-at-zero($grid-breakpoints, "$grid-breakpoints");

$container-max-widths: (
  sm: 540px,
  md: 720px,
  lg: 960px,
  xl: 1140px
) !default;

@include _assert-ascending($container-max-widths, "$container-max-widths");

Previously we switch parser by performance issues. Right now (for me) this is not a important development direction of this plugin.

[mrmlnc]

https://github.com/twbs/bootstrap/blob/master/scss/_variables.scss

vscode-css-languageservice: 82.553ms
scss-symbols-parser: 7.821ms  # with fix
postcss-scss: 25.152ms

[mrmlnc]

JFYI: https://github.com/microsoft/vscode-css-languageservice/blob/00a3873c2fc080b90622d8795c170d702779c724/src/services/scssNavigation.ts#L26

[mrmlnc]

As part of this ticket, we must fix the problem in the scss-symbols-parser.

https://github.com/mrmlnc/scss-symbols-parser/blob/e82822155161c2e4ffed2099b3448961e6fbde84/src/index.ts#L114

- } else if (token[0] === ')' && tokens[pos + 1] && tokens[pos + 1] === ';') {
+ } else if (token[0] === ')' && tokens[pos + 1] && tokens[pos + 1][0] === ';') {

[octref]

Yeah, me and @aeschli would be happy if we can share the parser can fix bug together.
FYI there's already a PR for adding @use and I'm planning to review and pull it in soon.
microsoft/vscode-css-languageservice#183