Refactor parameter handler

[mini-1235]

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Basic Info

Info	Please fill out this column
Ticket(s) this addresses	(add tickets here #1)
Primary OS tested on	Ubuntu
Robotic platform tested on	Tb4
Does this PR contain AI generated software?	Unit Test is partially generated by AI
Was this PR description generated by AI software?	Out of respect for maintainers, AI for human-to-human communications are banned

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Description of contribution in a few bullet points

• Refactor parameter handler

Description of documentation updates required from your changes

Description of how this change was tested

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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
• Should this be backported to current distributions? If so, tag with backport-*.

[mini-1235]

@SteveMacenski, if you agree on this PR I can rebase #5654 and #5446

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
nav2_graceful_controller/src/parameter_handler.cpp	98.60% <100.00%> (-0.10%)	⬇️
..._pure_pursuit_controller/src/parameter_handler.cpp	93.33% <100.00%> (-0.30%)	⬇️
nav2_util/include/nav2_util/parameter_handler.hpp	100.00% <100.00%> (ø)

... and 15 files with indirect coverage changes

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