Add namespace support for rviz costmap cost tool (backport #5268)

[mergify]

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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	My robot
Does this PR contain AI generated software?	(No; Yes and it is marked inline in the code)

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Description of contribution in a few bullet points

When adding the costmap cost tool in rviz, I noticed it does not return the value of global/local costmap tool when clicking, it is mainly because I have a namespace for my node, so I removed the "/" part

Description of documentation updates required from your changes

Description of how this change was tested

Tested on my robot

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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

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This is an automatic backport of pull request #5268 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 33e78d7 has failed:

On branch mergify/bp/jazzy/pr-5268
Your branch is up to date with 'origin/jazzy'.

You are currently cherry-picking commit 33e78d74.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   nav2_rviz_plugins/src/costmap_cost_tool.cpp

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[mergify]

@mergify[bot], all pull requests must be targeted towards the main development branch.
Once merged into main, it is possible to backport to @jazzy, but it must be in main
to have these changes reflected into new distributions.

[SteveMacenski]

@mini-1235 this didnt auto-backport. Can you open a Jazzy PR? I’m on the go today and can’t do those changes (even as trivially easy they are) on my phone.

[mini-1235]

@mini-1235 this didnt auto-backport. Can you open a Jazzy PR? I’m on the go today and can’t do those changes (even as trivially easy they are) on my phone.

Sure