Correct win_path index checks to allow for 0

[jalandis]

What does this PR do?

Fixes an issue with win_path module that improperly handled an index of 0.

Normalizes the path to allow for the example in bug report #45622. Allows the name to end with a path separator.

Fixes a win_path state comment ensuring an index of 0 is reported properly.

What issues does this PR fix or reference?

Fixes #45622

Previous Behavior

Failed to move a path from 1,2,... to 0.

New Behavior

test path:
  win_path.exists:
    - name: 'C:\Program Files\test\'
    - index: 0

----------
          ID: test path
    Function: win_path.exists
        Name: C:\Program Files\test\
      Result: True
     Comment: Moved C:\Program Files\test from index 2 to 0.
     Started: 15:05:44.304000
    Duration: 0.0 ms
     Changes:
              ----------
              index:
                  ----------
                  new:
                      0
                  old:
                      2

Summary for local
------------
Succeeded: 1 (changed=1)
Failed:    0
------------

Tests written?

Yes. Added assertion to validate adding to path at index 0.

Commits signed with GPG?

Yes

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[jalandis]

The state and module files were using 2 different but similar methods to sanitize the directory input. I am second guessing my decision to rely on the win_path modules normalize_dir method.

Should normalize_dir be moved to a utility module or switched to os.path.normpath?