Implement a Counting Lock

[erlingrj]

The counting lock can be implemented as a special CSR, one per HW thread which has the following semantics.

• The CSR has an owner, which is a thread, this can be static.
• Only the owner can write to the CSR
• Other threads can do a wait_until on the CSR. This operation will but the thread in idle mode until the CSR reaches that value.

This is intended to be used in quasi-static scheduling of Lingua Franca programs

[erlingrj]

@sberkun has expressed interest in pursuing this