Do not allow "." and ".." as UNC share names

[rmisev]

Because they have a special meaning and are removed by the URL parser.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (5abb4a4) 99.73% compared to head (99c3e20) 99.73%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #34 +/- ## ======================================= Coverage 99.73% 99.73% ======================================= Files 16 16 Lines 2291 2305 +14 ======================================= + Hits 2285 2299 +14 Misses 6 6 ```

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