Normalize Spack Win entry points (#38648)

* Normalize Spack Win entrypoints

Currently Spack has multiple entrypoints on Windows that in addition to
differing from *nix implementations, differ from shell to shell on
Windows. This is a bit confusing for new users and in general
unnecessary.
This PR adds a normal setup script for the batch shell while preserving
the previous "click from file explorer for spack shell" behavior.
Additionally adds a shell title to both powershell and cmd letting users
know this is a Spack shell

* remove doskeys

lib/spack/spack/environment/shell.py

@@ -48,8 +48,6 @@ def activate_header(env, shell, prompt=None, view: Optional[str] = None):
         cmds += 'set "SPACK_ENV=%s"\n' % env.path
         if view:
             cmds += 'set "SPACK_ENV_VIEW=%s"\n' % view
-        # TODO: despacktivate
-        # TODO: prompt
     elif shell == "pwsh":
         cmds += "$Env:SPACK_ENV='%s'\n" % env.path
         if view: