Add fast_brake command for HWP rapid spindown

[17-sugiyama]

Description

Update brake command of hwp_supervisor.

Motivation and Context

WG team is trying to measure the time constant by changing the hwp frequency rapidly e.g. +2Hz to -2Hz.
Current brake command is designed for gentle spindown and it takes >10 min to start inverse rotation.
New option of brake command is expected to take <2 min to spindown.
https://docs.google.com/presentation/d/1-kgAFn2sVR3R_Hp8_HcEYgZ8_SoNihm-UwsMn-Skxto/edit?usp=sharing

How Has This Been Tested?

Not tested yet

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[bbixler500]

In terms of content this all seems perfectly reasonable to me (although we should definitely test the fast brake process with an actual device before merging). However, structurally it might be best to merge the fast brake control states into the normal brake states, as they seem to share many of the same lines of code.