(feat) Add Variable Support in Wildcard Paths

[mwootendev]

Adds support for the issue described in #614 of sd-dynamic-prompts. The patch adds support for allowing variable refences within wildcard paths (e.g. __cars/${car}/types__). During the parsing phase, the variables will be retained in the path. During sampling, before resolving the wildcard, the variable is first resolved and replaced in the wildcard.

The update should allow support for variable replacement, including providing default values using the normal :default syntax. Some examples:

• ${gender=male}${section=upper} __clothes/${gender}/${section}__
• __clothes/${gender:female}/${section:lower}__
• __clothes/${gender:female}/${section:*}__

The test cases were updated to test a variety of scenarios.

[codecov-commenter]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (510d1e9) 97.47% compared to head (99778b7) 97.43%.

Files	Patch %	Lines
src/dynamicprompts/samplers/utils.py	88.57%	4 Missing :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #110 +/- ## ========================================== - Coverage 97.47% 97.43% -0.05% ========================================== Files 77 77 Lines 3249 3352 +103 ========================================== + Hits 3167 3266 +99 - Misses 82 86 +4 ```

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[mwootendev]

@akx Thank you for the in-depth feedback. I'll be honest, this is my first time trying work with Python, so I'm unfamiliar with many of the idioms. I've mostly done Java, JavaScript, and TypeScript development, so I appreciate the Python guidance. I hope this last update resolved all of your concerns.

[akx]

@mwootendev Tests seem to be now failing 😩

[mwootendev]

@mwootendev Tests seem to be now failing 😩

This should be resolved in the latest push. In the case where the variable was None it failed that check.