[nav2_behavior_tree] Add force_use_current_pose to ComputePathToPoseAction

[doisyg]

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Basic Info

Info	Please fill out this column
Ticket(s) this addresses
Primary OS tested on	(Ubuntu
Robotic platform tested on	Dexory robot
Does this PR contain AI generated software?	No

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Description of contribution in a few bullet points

Adds an optional input field force_use_current_pose to the ComputePathToPoseAction BT node.
When set to true, use the current robot pose, even if start is provided (effectively ignoring it).
This is useful when calling several time the ComputePathToPoseAction in a BT with different arguments and wanting to use the current pose of the robot after a call where start was used (and hence existing in the blackboard).

Description of documentation updates required from your changes

If accepted in this state, then update this: https://docs.nav2.org/configuration/packages/bt-plugins/actions/ComputePathToPose.html#computepathtopose

Description of how this change was tested

Extensively tested on my physical robot platform (but backported from Dexory jazzy branch)

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Future work that may be required in bullet points

For Maintainers:

• Check that any new parameters added are updated in docs.nav2.org
• Check that any significant change is added to the migration guide
• Check that any new features OR changes to existing behaviors are reflected in the tuning guide
• Check that any new functions have Doxygen added
• Check that any new features have test coverage
• Check that any new plugins is added to the plugins page
• If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists