Remove the redundant layer "hl"

[StarrryNight]

Description

We currently have a redundant folder layer in the software directory named hl:
e.g. //software/ai/hl/stp/play:all_plays
The folder contains nothing but stp, which contains all the skill tactics and play stuff.
This PR removes the hl folder and moves stp up to ai.

Testing Done

bazel build \\software\... passes

Resolved Issues

#1917

Length Justification and Key Files to Review

Review Checklist

It is the reviewers responsibility to also make sure every item here has been covered

• Function & Class comments: All function definitions (usually in the .h file) should have a javadoc style comment at the start of them. For examples, see the functions defined in thunderbots/software/geom. Similarly, all classes should have an associated Javadoc comment explaining the purpose of the class.
• Remove all commented out code
• Remove extra print statements: for example, those just used for testing
• Resolve all TODO's: All TODO (or similar) statements should either be completed or associated with a github issue

[Andrewyx]

Is this hash addition intended? I can't comment on that line in the PR: src/extlibs/er_force_sim/src/amun/framework
https://github.com/UBC-Thunderbots/Software/pull/3977/changes#diff-e0ac4be0db1fbe7978faf738d5c498fb5ac1072618b45d543e388ff11971c24eR1

[GrantYu9]

Mostly looks good to me. I only had a small question/comment but it didn't seem to be too major.