Allow no support package in LocalPackageMeshLoader

[yck011522]

This will allow the LocalPackageMeshLoader to process robot
packages that does not have a support_package sub folder. This is used for loading packages from the local_cache_directory of the RosFileServerLoader.

What type of change is this?

• Bug fix in a backwards-compatible manner.
• New feature in a backwards-compatible manner.
• Breaking change: bug fix or new feature that involve incompatible API changes.
• Other (e.g. doc update, configuration, etc)

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• I added a line to the CHANGELOG.md file in the Unreleased section under the most fitting heading (e.g. Added, Changed, Removed).
• I ran all tests on my computer and it's all green (i.e. invoke test).
• I ran lint on my computer and there are no errors (i.e. invoke lint).
• I have added tests that prove my fix is effective or that my feature works.
• I have added necessary documentation (if appropriate)

[yck011522]

For the interest of not changing signature, I did not change the init signature to have support_package = None

[gonzalocasas]

Please add a test to verify that this works, because I see there are calls to build_path that rely on support_package being there and while they will still work now, it feels a bit fragile.

[yck011522]

Please add a test to verify that this works, because I see there are calls to build_path that rely on support_package being there and while they will still work now, it feels a bit fragile.

I can see that there are calls to build_path , maybe I should make a switch there too to not include support_package if it is empty.

Regarding test, I'm not sure what you are refering to as fragile, can you elaborate more or explain how you would design the test? @gonzalocasas