Update ATMCS interface according to discussion with Patrick, Rolando and Russell

Changes:

• Add M3 motor encoder data to existing telemetry topics.
• Remove ATMountState enumeration values that overlap summary state.
• Remove M3State enumeration values that overlap summary state.
• Reorder fields in the mountEncoders telemetry topic to the standard order used everywhere else.
• Rename command topic fields that are ignored to ignored.
• Rename brake fields from engage to engaged.
• Remove m3RotatorDetentLimitSwitch to m3RotatorDetentSwitches and remove Detent from the field names.
• Remove redundant State suffix from ATMountState_ and M3State_ events, e.g. change M3State_DisabledState to M3State_Disabled.
• Add documentation for all topics (and fix existing incorrect documentation).