Refactor build workspace on save feature

[ramya-rao-a]

The PR refactors the work done around build on save feature in #1023 to fix the below issues

• The issue found in vscode-go doesn't work well with symlinked directroy #846 is back with the work done in Run on-save tools for entire workspace #1023
• The -i flag which results in faster builds doesn't get used when building workspace
• The vendor packages get built as well when building workspace See Build Workspace except vendor folder #1060

[ramya-rao-a]

@vapourismo Since you worked on #1023, can you take a look at this PR? You might find something I missed.

[vapourismo]

I can't reliably review it right now, sorry.