feat(gnss_poser): add orthometric height as a option

[farukbaykara]

Description

• Added to gnss_poser package as an option to convert ellipsoid height to orthometric height.
• Added a height_system parameter to gnss_poser.launch and user can select whether use ellipsoid to orthometric height conversion.
• Output always will be orthometric height.

Closes: #3693

Tests performed

Tested using bag collected from YTU Davutpasa campus with Robione robot.
Will be tested on vehicle too.

Not applicable.

Effects on system behavior

Not applicable.

Pre-review checklist for the PR author

The PR author must check the checkboxes below when creating the PR.

• I've confirmed the contribution guidelines.
• The PR follows the pull request guidelines.

In-review checklist for the PR reviewers

The PR reviewers must check the checkboxes below before approval.

• The PR follows the pull request guidelines.

Post-review checklist for the PR author

The PR author must check the checkboxes below before merging.

• There are no open discussions or they are tracked via tickets.

After all checkboxes are checked, anyone who has write access can merge the PR.

[YamatoAndo]

I have confirmed "Orthometric Height" and "Ellipsoid Height" using the tutorial dataset.
LGTM!

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: -0.01 ⚠️

Comparison is base (2afabd0) 14.46% compared to head (8131ed5) 14.46%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3740      +/-   ##
==========================================
- Coverage   14.46%   14.46%   -0.01%     
==========================================
  Files        1432     1432              
  Lines      100864   100872       +8     
  Branches    29779    29779              
==========================================
  Hits        14588    14588              
- Misses      70429    70437       +8     
  Partials    15847    15847              

Flag	Coverage Δ		*Carryforward flag
differential	0.00% <0.00%> (?)
total	14.46% <ø> (+<0.01%)	⬆️	Carriedforward from 2afabd0

*This pull request uses carry forward flags. Click here to find out more.

Impacted Files	Coverage Δ
sensing/gnss_poser/include/gnss_poser/convert.hpp	0.00% <0.00%> (ø)
sensing/gnss_poser/src/gnss_poser_core.cpp	0.00% <0.00%> (ø)

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.