Add fixes and enhancements related to `MocoGeneralizedForceTrackingGoal`

[nickbianco]

Brief summary of changes

The exampleMocoTrack subexample using MocoGeneralizedForceTrackingGoal did not work out-of-the-box due to changes in the source code that were not propagated to the example files. The example failed because setWeightForGeneralizedForce expected a generalized force name (e.g., "ankle_angle_r_moment") but was currently being given only the coordinate name. This PR fixes this inconsistency and includes the following improvements:

• Adds setWeightForGeneralizedForcePattern to allow setting weights for multiple coordinates simultaneously using regex patterns.
• Minor updates to the documentation.
• Changed some variable names in the implementation to improve clarity.

Testing I've completed

Ran exampleMocoTrack locally.

Looking for feedback on...

CHANGELOG.md (choose one)

• no need to update because...example not officially released yet.

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This change is 

[nickbianco]

Thanks @AllisonJohn and @carmichaelong!