Don't compile user agent regexes on every call

[matrixbot]

This issue was originally created by @sandhose at matrix-org/matrix-authentication-service#2504.

We have a few regexes that are compiled on each UA parsing. Those should be in static cells instead and compiled on startup instead

https://github.com/matrix-org/matrix-authentication-service/blob/5b5346ebb77dd10fbc49c9641e794ba70aed76d4/crates/data-model/src/user_agent.rs#L48

[sandhose]

This has been done in #4449