Support azure signtool

[marcoesters]

Description

Add support for AzureSignTool to sign Windows installers. AzureSignTool uses Azure key vaults, which do not use certificate files on disk. To achieve this, this PR:

• Adds a windows_signing_tool keyword that selects the tool to sign. This key determines whether to sign the installer instead of signing_certificate, which makes signing more extensible.
• Creates classes for Windows signing tools.
• Adds documentation for all environment variables for both SignTool and AzureSignTool.
• Allows signtool.exe to use a different digest algorithms.

Since this requires access to Azure, tests cannot be added for this feature.

Closes #767.

Checklist - did you ...

• [X] Add a file to the news directory (using the template) for the next release's release notes?
• [X] Add / update necessary tests?
• [X] Add / update outdated documentation?

[marcoesters]

so I wonder if it's feasible to have a some secrets added to a dummy vault (or something that implements the same API).

I will work internally on this and will see that I can get tests into this PR.

[marcoesters]

I added integration tests and secrets were added to the repository. However, the secrets will not be available for anybody who submits a PR from the fork, which will cause the tests to fail. The tests do execute the correct command though: https://github.com/conda/constructor/actions/runs/8760110611/job/24044501617#step:9:2133

Those tests will have to be skipped until merged into main. So, we will have to add As discussed with @jaimergp offline, the best way to go here is to add test failure reporting as they do for conda-libmambda-solver: https://github.com/conda/conda-libmamba-solver/blob/efa3b84141e4ff777928aaae952fac417b059091/.github/workflows/tests.yml#L680-L690

This requires a token, so I will convert this PR into draft until that infrastructure is in place.

Additional things I found:

• The environment is not copied into the subprocess on Windows when no extra environment variables are set. On POSIX, this is handled by the subprocess module, but not for Windows. So, I copy the environment explicitly for all to get conistent behavior.
• The debugging section was not in any TOC tree for the documentations, so I added it.