Add min_distance_to_obstacle parameter to RPP

[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's robot
Does this PR contain AI generated software?	No

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Description of contribution in a few bullet points

This PR adds the parameter min_distance_to_obstacle to stop in front of an obstacle based on distance and not only time to collision

Description of documentation updates required from your changes

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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

[SteveMacenski]

Maybe I'm also missing the detail: do you want these both conditions to need to be satisfied to stop, or just one or other other?

If, for instance, you want both, which I think you do, we could instead do something like:

max_allowed_time_to_collision_check = std::max(params_->max_allowed_time_to_collision_up_to_carrot, params_->min_distance_to_obstacle * linear_vel); and use max_allowed_time_to_collision_check in the while loop condition instead of the parameter. I think that would make this intent more clear.