fix(BuildTools): forward --ros2 and --dds-middleware to UE4 editor command line

[JArmandoAnaya]

PR: fix(BuildTools): forward --ros2 and --dds-middleware to UE4 editor command line

Branch: fix/issue-9511-ros2-launch
Base: ue4-dev

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Description

Fixes #9511

This PR is blocked on #9645.

When running make launch ARGS="--ros2", the --ros2 flag is consumed by BuildCarlaUE4.sh
for build-time configuration (OptionalModules.ini) but never forwarded to the UE4 editor
process. At runtime, CarlaSettings.cpp checks FParse::Param(TEXT("-ros2")) on the command
line, which always fails because the flag is missing.

This PR adds a forwarding block after the argument-parsing loop in both build scripts:

BuildCarlaUE4.sh:

• New DDS_MIDDLEWARE variable and --dds-middleware getopt option
• After parsing, appends --ros2 and --dds-middleware=<value> to EDITOR_FLAGS

BuildCarlaUE4.bat:

• After parsing, appends --ros2 to EDITOR_FLAGS when USE_ROS2 is true
• No --dds-middleware on Windows (only FastDDS is supported)

After the fix, make launch ARGS="--ros2" produces:

UE4Editor CarlaUE4.uproject -vulkan --ros2

And make launch ARGS="--ros2 --dds-middleware=cyclonedds" produces:

UE4Editor CarlaUE4.uproject -vulkan --ros2 --dds-middleware=cyclonedds

Where has this been tested?

• Platform: Ubuntu 22.04
• ROS2 verification: osrf/ros:humble-desktop container, ros2 topic list confirms
  /clock and all CARLA topics are published
• Unreal Engine: 4.26

Script argument-parsing verified with 6 unit tests covering all flag combinations
(--ros2 only, --dds-middleware only, both, neither, combined with --editor-flags).

Possible Drawbacks

None. The forwarding is additive and only activates when --ros2 or --dds-middleware is
explicitly passed. Existing workflows without these flags are unaffected.

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This change is 

[update-docs]

Thanks for opening this pull request! The maintainers of this repository would appreciate it if you would update our CHANGELOG.md based on your changes.

[LuisPovedaCano]

The Windows CI/CD failure is not caused by this PR's changes.
The cause is that the branch is 2 commits behind ue4-dev and is missing commit 364fd34
fatal error C1083: Cannot open include file: 'carla/ros2/dds/DDSMiddleware.h': No such file or directory
To fix it, just update the branch against current ue4-dev

[JArmandoAnaya]

Hello! Done, I already rebased from ue4-dev.

[JArmandoAnaya]

It looks like Windows CI is still failing, but I saw the error, and it doesn't seem related to this PR or the ROS2 fixes.