Fixes and optimizations in logger:
* fixed possible buffer overflow when logging
logs over line buffer size;
* reduced max log line length to 2048;
* moved pubsetbuf before file opening;
* log file stream buffer created once
in logger ctor;
* updatet UTs;
* additional minor cleanup.
- Dump logs to file every 10 sec.
- max file size is 50 MB
(after reaching it, no more logs will be logged),
- Add `LockGuard` with locking mechanism
supporting IRQ and use it in `Logger`.
- Fix minor style issues in `Logger`.
- Add `mount_user_lfs_partition.py` script for mounting LFS on Linux FS
in order to get `MuditaOS.log` file from `user` partition
