[feat] Add SpinLock interface

[hgruniaux]

See:

• https://www.kernel.org/doc/html/latest/locking/spinlocks.html
• https://docs.zephyrproject.org/apidoc/latest/group__spinlock__apis.html
• https://stackoverflow.com/questions/1957398/what-exactly-are-spin-locks

Note, the atomic library is freestanding in C++

Ideas to optimize:

• https://rigtorp.se/spinlock/
• Use of the yield instruction. See https://stackoverflow.com/questions/70069855/is-there-a-yield-intrinsic-on-arm.

[hgruniaux]

Done in #33