Escape paths w/single quotes before passing to powershell in sq strings

[rkeithhill]

If the user's install path has a single quote in it e.g C:\Users\Night's Watch then the command line we supply to powershell fails to parse because we have a single quote inside of a single-quoted string e.g.:

powershell.exe -Command "& 'C:\Users\Night's Watch\.vscode\extenions...' …"

I believe this PR to be done but I'd like to see if it fixes the original issue for ajpaul18. Update: the fix was verified.

Fix #1404

PR Checklist

Note: Tick the boxes below that apply to this pull request by putting an x between the square brackets.
Please mark anything not applicable to this PR NA.

• PR has a meaningful title
• Summarized changes
• This PR is ready to merge and is not work in progress
  • If the PR is work in progress, please add the prefix WIP: to the beginning of the title and remove the prefix when the PR is ready

[rjmholt]

I've tested start up on Linux with both /path/Robert's Foo/dir/ and /path/My "Foo"/dir/ and both work 👍

[rjmholt]

Looks like the folding tests are failing — not sure how to fix that

[rkeithhill]

See PR #1410.