fix(dev): remove gitpod support and update docs

[kenibrewer]

Description

Rationale for deprecating gitpod dev environment support in attached issue.

• Removes gitpod configuration
• Updates docs
• Fixes incorrect create a codespace link

Closes #346

What is the nature of your change?

• Bug fix (fixes an issue).
• This change requires a documentation update.

Checklist

Please ensure that all boxes are checked before indicating that a pull request is ready for review.

• I have read the CONTRIBUTING.md guidelines.
• My code follows the style guidelines of this project.
• I have performed a self-review of my own code.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have deleted all non-relevant text in this pull request template.

[codecov-commenter]

Codecov Report

Merging #347 (890b715) into main (871b633) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #347   +/-   ##
=======================================
  Coverage   95.40%   95.40%           
=======================================
  Files          56       56           
  Lines        3134     3134           
=======================================
  Hits         2990     2990           
  Misses        144      144           

Flag	Coverage Δ
unittests	95.40% <ø> (ø)

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[d33bs]

Thanks for this, LGTM. Sorry to see the option go away but I understand the reasons why.

Aside: not overly worried, but I wonder about eventual pricing changes with GitHub on this front and what could happen when/if that takes place.