Bump version to 10.0.4.dev0

See merge request !883

Update cpptango version, docs and bump version for 10.0.4 release

See merge request !971

The change was missed in one place.  Now use a shared variable.

Also moved the Windows cppTango version to the top level file so we can update
everything in one place.  It differs from the conda-forge versioning for release
candidates. E.g., we would use `CPP_TANGO_VERSION: "10.0.0rc1"` for conda package,
but we would need `CPP_TANGO_VERSION_TAG: "10.0.0-rc1"` for the Windows package.

Fix windows ci, backport !822, update docs

See merge request !974