Prevent lwc and lightning extensions activating in non-Salesforce projects

[lcampos]

What does this PR do?

These changes will prevent LWC & Lightning extensions activating in non-Salesforce projects which cause the salesforce-core extension to activate and throw errors.

This addresses issues #1988 and #2065

What issues does this PR fix or reference?

[codecov]

Codecov Report

Merging #2070 into release/v48.6.0 will increase coverage by 0.02%.
The diff coverage is n/a.

@@                 Coverage Diff                 @@
##           release/v48.6.0    #2070      +/-   ##
===================================================
+ Coverage            73.08%   73.10%   +0.02%     
===================================================
  Files                  236      236              
  Lines                 8804     8804              
  Branches              1003     1003              
===================================================
+ Hits                  6434     6436       +2     
+ Misses                2128     2126       -2     
  Partials               242      242              

Impacted Files	Coverage Δ
...forcedx-vscode-core/src/channels/channelService.ts	85.71% <0.00%> (+2.38%)	⬆️
...code-lwc/src/testSupport/testRunner/testWatcher.ts	82.85% <0.00%> (+2.85%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update bb8ac71...b0c2968. Read the comment docs.