Bug 964601 - [Settings] Add usb transter panel

- rename system storage to usb_storage
- have split switch
- have usb storage settings in storage_item
Bug 1022192 - Add more log for utils-xpc:writeContent()
Bug 1055981 - fix typo in teardown of homescreen_launcher_test.js
Bug 1053613 - Lockscreen PIN keypad: backspace key misaligned & wrong, vertical separators missing, last row too high
Merge pull request #22879 from mnjul/bug_1053613_lockscreen_pin_bckspc_lastrow_vertical_separator

Bug 1053613 - Lockscreen PIN keypad: backspace key misaligned & wrong, vertical separators missing, last row too high. r=gweng
Merge pull request #23305 from yurenju/log-write-content

Bug 1022192 - Add more log for utils-xpc:writeContent()
Merge pull request #23015 from gasolin/issue-964601

Bug 964601 - [Settings] Add usb transter panel, r=eragon,alive
Merge pull request #23339 from dwi2/bug1055981

Bug 1055981 - fix typo in teardown of homescreen_launcher_test.js
Bug 1012568 - replace all tab to 2 spaces in Makefile except makefile rules R=yurenju