Setup initial workflow for building on Windows.

[ScottTodd]

Progress on #36.

This adds a new workflow, triggered as part of ci.yml, that configures and builds a subset of the project.

Future changes will:

• Switch to a more powerful self-hosted runner instead of using standard GitHub-hosted runners (we have some runners but they need some configuration to be able to run the repo tool without SSL: CERTIFICATE_VERIFY_FAILED errors)
• Build more subprojects (this will patches or upstream changes to each subproject to improve portability)

[ScottTodd]

Argh, more download flakes: https://github.com/nod-ai/TheRock/actions/runs/13190519640/job/36822474141?pr=73#step:11:765

[53/72] Stage installing sub-project therock-eigen
-- Install configuration: "Release"
[54/72] Performing download step (download, verify and extract) for 'therock-FunctionalPlus-sources'
FAILED: third-party/FunctionalPlus/therock-FunctionalPlus-sources_fetch/src/therock-FunctionalPlus-sources-stamp/therock-FunctionalPlus-sources-download D:/a/TheRock/TheRock/build/third-party/FunctionalPlus/therock-FunctionalPlus-sources_fetch/src/therock-FunctionalPlus-sources-stamp/therock-FunctionalPlus-sources-download 
C:\Windows\system32\cmd.exe /C "cd /D D:\a\TheRock\TheRock\build\third-party\FunctionalPlus && "C:\Program Files\CMake\bin\cmake.exe" -DCMAKE_MESSAGE_LOG_LEVEL=VERBOSE -P D:/a/TheRock/TheRock/build/third-party/FunctionalPlus/therock-FunctionalPlus-sources_fetch/src/therock-FunctionalPlus-sources-stamp/download-therock-FunctionalPlus-sources.cmake && "C:\Program Files\CMake\bin\cmake.exe" -DCMAKE_MESSAGE_LOG_LEVEL=VERBOSE -P D:/a/TheRock/TheRock/build/third-party/FunctionalPlus/therock-FunctionalPlus-sources_fetch/src/therock-FunctionalPlus-sources-stamp/verify-therock-FunctionalPlus-sources.cmake && "C:\Program Files\CMake\bin\cmake.exe" -DCMAKE_MESSAGE_LOG_LEVEL=VERBOSE -P D:/a/TheRock/TheRock/build/third-party/FunctionalPlus/therock-FunctionalPlus-sources_fetch/src/therock-FunctionalPlus-sources-stamp/extract-therock-FunctionalPlus-sources.cmake && "C:\Program Files\CMake\bin\cmake.exe" -E touch D:/a/TheRock/TheRock/build/third-party/FunctionalPlus/therock-FunctionalPlus-sources_fetch/src/therock-FunctionalPlus-sources-stamp/therock-FunctionalPlus-sources-download"
-- Downloading...
   dst='D:/a/TheRock/TheRock/build/third-party/FunctionalPlus/therock-FunctionalPlus-sources_fetch/src/v0.2.25.tar.gz'
   timeout='none'
   inactivity timeout='none'
-- Using src='https://github.com/Dobiasd/FunctionalPlus/archive/refs/tags/v0.2.25.tar.gz'
-- Retrying...
-- Using src='https://github.com/Dobiasd/FunctionalPlus/archive/refs/tags/v0.2.25.tar.gz'
-- Retry after 5 seconds (attempt #2) ...
-- Using src='https://github.com/Dobiasd/FunctionalPlus/archive/refs/tags/v0.2.25.tar.gz'
-- Retry after 5 seconds (attempt #3) ...
-- Using src='https://github.com/Dobiasd/FunctionalPlus/archive/refs/tags/v0.2.25.tar.gz'
-- Retry after 15 seconds (attempt #4) ...
-- Using src='https://github.com/Dobiasd/FunctionalPlus/archive/refs/tags/v0.2.25.tar.gz'
-- Retry after 60 seconds (attempt #5) ...
-- Using src='https://github.com/Dobiasd/FunctionalPlus/archive/refs/tags/v0.2.25.tar.gz'
CMake Error at therock-FunctionalPlus-sources_fetch/src/therock-FunctionalPlus-sources-stamp/download-therock-FunctionalPlus-sources.cmake:163 (message):
  Each download failed!

    error: downloading 'https://github.com/Dobiasd/FunctionalPlus/archive/refs/tags/v0.2.25.tar.gz' failed
          status_code: 35
          status_string: "SSL connect error.  If this is due to https certificate verification failure, one may set environment variable CMAKE_TLS_VERIFY=0 to suppress it."
          log:
          --- LOG BEGIN ---
          timeout on name lookup is not supported

  Host github.com:443 was resolved.

[ScottTodd]

Converting to draft until I can sync and test this. Looks like a few issues popped up. Most recently https://github.com/nod-ai/TheRock/actions/runs/13207156066/job/36872929040?pr=73#step:11:458 FileNotFoundError: [WinError 3] The system cannot find the path specified: 'D:\\a\\TheRock\\TheRock\\build\\base\\rocm_smi_lib\\stage' (which I was disabling, may need to disable in a few new locations)

[ScottTodd]

Rebased and got a successful run. I'll retry the job a few times to make sure it's stable. Then in a future PR we can switch to one of our self hosted runners / clusters. Right now this mostly exercises the source fetching and baseline CMake configure + build.

[ScottTodd]

Recent runs are 3/3 successes. Merging :D