FuriHalSerial: Fix RXFNE interrupt hang

[WillyJL]

What's new

• fixes Flipperzero crashes when GPS is attached to GPIO #4081: FuriHalSerial was unsetting user callback before disabling interrupt, leading to a few clock cycles between which an RXFNE uart interrupt could be triggered without the data being read and thus the flag remaining set, leading to the same interrupt being invoked in loop forever and spending 100% cpu time in interrupt mode, hanging the system
• made expansion worker stop async rx earlier to avoid more potential issues
• also made expansion worker wake up on error flags, im guessing it was accidentally not included

Verification

• enable settings > expansion modules > listen uart and plug a noisy uart module in the relative uart channel
• this could be a gps module, an esp32 crashing and bootlooping outputting a ton of logs, basically anything that outputs a lot of data on uart
• flipper should not freeze
• also, ensure things like vgm and other serial apps work correctly without getting regressions

Checklist (For Reviewer)

• PR has description of feature/bug or link to Confluence/Jira task
• Description contains actions to verify feature/bugfix
• I've built this code, uploaded it to the device and verified feature/bugfix