Support result codes for path planner in benchmarking

[AlexeyMerzlyakov]

Support new result codes of Path Planner in Nav2 benchmarking suite, added since 1c10617

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Basic Info

Info	Please fill out this column
Ticket(s) this addresses	#3043
Primary OS tested on	Ubuntu 20.04
Robotic platform tested on	TB3 simulation

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Description of contribution in a few bullet points

• Added the support of non-NULL return states from computePlan() (passed as action_server->terminate_current(result) with non-empty argument).
• Fixed the bug in planning_benchmark_bringup.py when the Map Server can not start with non-existing map.

Description of documentation updates required from your changes

Not required

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For Maintainers:

• Check that any new parameters added are updated in navigation.ros.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

[mergify]

@AlexeyMerzlyakov, please properly fill in PR template in the future. @SteveMacenski, use this instead.

• Check that any new parameters added are updated in navigation.ros.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