feat: Use open-source Terraform Provider

[kylecarbs]

This removes our internal Terraform Provider, and opens it to the world!

[codecov]

Codecov Report

Merging #403 (d41c369) into main (bf0ae8f) will decrease coverage by 0.15%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #403      +/-   ##
==========================================
- Coverage   68.41%   68.25%   -0.16%     
==========================================
  Files         159      158       -1     
  Lines        9318     9227      -91     
  Branches       73       73              
==========================================
- Hits         6375     6298      -77     
+ Misses       2312     2307       -5     
+ Partials      631      622       -9     

Flag	Coverage Δ
unittest-go-macos-latest	62.65% <100.00%> (-0.41%)	⬇️
unittest-go-ubuntu-latest	67.45% <100.00%> (+0.11%)	⬆️
unittest-go-windows-2022	62.23% <0.00%> (+0.06%)	⬆️
unittest-js	66.02% <ø> (ø)

Impacted Files	Coverage Δ
provisionersdk/agent.go	100.00% <100.00%> (+22.22%)	⬆️
provisionersdk/serve.go	35.13% <0.00%> (-8.11%)	⬇️
peer/conn.go	78.00% <0.00%> (-3.59%)	⬇️
codersdk/provisionerdaemons.go	58.46% <0.00%> (-3.08%)	⬇️
provisioner/echo/serve.go	57.50% <0.00%> (-2.50%)	⬇️
provisionerd/provisionerd.go	78.30% <0.00%> (-0.92%)	⬇️
peer/channel.go	83.04% <0.00%> (-0.59%)	⬇️
coderd/provisionerdaemons.go	57.60% <0.00%> (+0.54%)	⬆️
peerbroker/proxy.go	59.30% <0.00%> (+1.74%)	⬆️

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[bryphe-coder]

Nice! 🎉

[bryphe-coder]

Thanks for referencing this back!