Fix the inner loop development when editing markdown files

[bart-vmware]

This PR replaces the dotnet docfx build step with a script that downloads our custom binaries and then executes the same command.

This enables quick iteration on editing handwritten documentation, ie:

1. Edit a markdown file in docs/docs and save it
2. Run the script
3. Use the existing command to start the website

To further edit files, you can leave the website running. Saving your changes and running the script again updates the website content.

[github-actions]

External link checking results

Status	Count
🔍 Total	1885
✅ Successful	1072
⏳ Timeouts	0
🔀 Redirected	0
👻 Excluded	813
❓ Unknown	0
🚫 Errors	0
⛔ Unsupported	0

Full Github Actions output

[github-actions]

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[bart-vmware]

External link checking results

I don't know why these fail. When running locally, no errors are reported.

[TimHess]

External link checking results

I don't know why these fail. When running locally, no errors are reported.

Looks like there was a server error... Maybe there was a deployment happening when the checker ran the first time? Subsequent runs would have used the cache. I cleared the cache and the scan is clean now

[TimHess]

LGTM