CSS - Search in parent folders for node module resolution

[penx]

Replaces my previous PR #79651 by implementing recommendations from @octref on #78894 .

Further to #70693 which was reworked by @aeschli in 8f72934 due to issues with require.resolve and webpack.

• Fixes [scss] link doesn't work with ~Tilde to search in node module or webpack alias #78894
• Fixes Ctrl+click (go to file) doesn't work for saas-loader ~ imports (node_modules) vscode-css-languageservice#136

The current implementation for microsoft/vscode-css-languageservice#136 resolves the path to a CSS module but only looks for node_modules in the same folder as the CSS file, which for many use cases is not sufficient.

This PR updates resolvePathToModule so that it looks in parent folders for the existence of node_modules/module-name all the way up to the workspace root, following node module resolution.

Alternative approaches were raised in #79651 and this approach was preferred by @octref in #78894 (comment).

[penx]

@octref @aeschli is there anything holding up merging this PR? Any more I can do?

[penx]

@Tyriar any more I can do to get this in to a release?

[Tyriar]

@penx I have nothing to do with this, I simply pushed it out as it didn't make it into the release.

[penx]

#20200323.20 failed
BackupRestorer Restore backups:
11980
Error: Backup: Could not find meta end marker in vscode

After rebasing off master, the above error is reported. Pretty sure this is unrelated to this PR and tests should be rerun

[aeschli]

@penx Sorry for the wait.
Can you also add a test case in https://github.com/microsoft/vscode/blob/master/extensions/css-language-features/server/src/test/links.test.ts ?

[penx]

@aeschli no worries, I've added a test and reordered commits to show test fail then pass

[aeschli]

Thanks @penx!