[MLA-1879] culture-invariant sorting for sensors and actuators

[chriselion]

Proposed change(s)

Previously, sensors and actuators were sorted using the local culture for string comparisons (i.e. using string.CompareTo with default arguments). A potential bug with this is that sensors would be sorted one way during training, but differently when performance inference on a different end user's system. This changes sorting to use StringComparison.InvariantCulture, which is consistent everywhere (this was initially using Ordinal sorting, but that differs a lot from from the local en-US sorting)

Note that this might break existing models after upgrading if the sensor names are sorted differently. I believe that this is preferable to not making the change, since the alternative would end up causing more breakages further in the future, in a harder-to-diagnose way (i.e. after a game ships).

Useful links (Github issues, JIRA tickets, ML-Agents forum threads etc.)

https://docs.microsoft.com/en-us/dotnet/api/system.globalization.compareoptions?view=net-5.0
https://docs.microsoft.com/en-us/globalization/locale/sorting-and-string-comparison
https://docs.microsoft.com/en-us/dotnet/api/system.globalization.cultureinfo.invariantculture?view=net-5.0

Types of change(s)

• Bug fix
• Breaking change

Checklist

• Added tests that prove my fix is effective or that my feature works
• Updated the changelog (if applicable)
• Updated the documentation (if applicable)
• Updated the migration guide (if applicable)

Other comments