[22850] Fix python code generation for bounded strings (backport #440)

[mergify]

Description

This PR introduces the following improvements on the code generated for SWIG interfaces:

1. A setter for fixed_string members receiving a standard string is added.
2. A %template for each fixed_string member is generated.

This allows setting bounded string members with either of the following alternatives:

1. struct_name.member_name("string value")

2. fixed_str = fixed_string_16("string value")
   struct_name.member_name(fixed_str)
   

@Mergifyio backport 4.0.x

Contributor Checklist

• Commit messages follow the project guidelines.

• Tests that thoroughly check the new feature have been added/Regression tests checking the bug and its fix have been added; the added tests pass locally

  • See [22851] Add support for bounded strings Fast-DDS-python#209 for the added tests

• N/A: New feature has been documented/Current behavior is correctly described in the documentation.

• Applicable backports have been included in the description.

Reviewer Checklist

• The PR has a milestone assigned.
• The title and description correctly express the PR's purpose.
• Check contributor checklist is correct.
• Check CI results: changes do not issue any warning.
• Check CI results: failing tests are unrelated with the changes.

---

This is an automatic backport of pull request #440 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 8eaca9a has failed:

On branch mergify/bp/3.3.x/pr-440
Your branch is up to date with 'origin/3.3.x'.

You are currently cherry-picking commit 8eaca9a.
  (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:   src/main/java/com/eprosima/fastcdr/idl/templates/TypesSwigInterface.stg

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

[MiguelCompany]

@Mergifyio rebase

[mergify]

rebase

✅ Branch has been successfully rebased

[MiguelCompany]

@Mergifyio rebase

[mergify]

rebase

✅ Branch has been successfully rebased

[MiguelCompany]

@Mergifyio rebase

[mergify]

rebase

✅ Branch has been successfully rebased

[MiguelCompany]

LGTM with green CI