* Unit tests: add "exists" to furi_record tests
* Unit tests: mu_warn, storage 64k test
* Storage: read/write over 64k
* Unit tests: moar tests for storage r/w for >64k cases
* Apps, libs: replace uint16_t with size_t on storage r/w operations
* Unit tests: better data pattern, subghz: warning if transmission is prohibited
Co-authored-by: あく <alleteam@gmail.com>