Fix the issue #16317 in judging module names starting with base_model_prefix
Author: hui-wan
Pull request: yes

This fixed #16317:
```
Keys are still reported as "missing" during model loading even though
 specified in `_keys_to_ignore_on_load_missing`
```
 as described in detail in #16317.

The cause of the issue is:
  * The code that judges if a module name has the `base_model_prefix`
    would match it with *any* beginning part of the name. This caused
    the first part of the module name being stripped off unexpectedly
    sometimes, hence not able to match the prefix in
    `_keys_to_ignore_on_load_missing`.

Fix:
 * Match `base_model_prefix` as a whole beginning word followed by
   `.` in module names.

Also added test into `test_modeling_common`.

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Fixes # (issue)


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Comments:
_The documentation is not available anymore as the PR was closed or merged._

See discussion on #16317 :-)