[FL-1946] RPC App launch (#758)

* RPC: Add App start, lock status
 - Add RPC commands Application start, lock status acquiring.
 - Write tests for RPC App system.
 - Replace Unit Tests application with CLI command. This is for CI needs and for tests that run application.
* Fix NDEBUG build
* Update PB submodule
* Fix RPC print (ENABLE DEBUG PRINT!)
* snprintf -> string_t
* Fix Hard Fault (early mutex free)
* printf -> string_t, format, enable tests
* Update submodule: protobuf
* Applications: rollback unit test naming scheme.

Co-authored-by: Aleksandr Kutuzov <alleteam@gmail.com>

applications/applications.mk

@@ -42,7 +42,6 @@ APP_BLINK	= 1
 APP_IRDA_MONITOR = 1
 APP_KEYPAD_TEST = 1
 APP_SD_TEST	= 1
-APP_UNIT_TESTS = 0
 APP_VIBRO_DEMO = 1
 APP_USB_TEST = 1
 endif
@@ -60,7 +59,7 @@ SRV_GUI		= 1
 endif
 
 
-APP_UNIT_TESTS	?= 0
+APP_UNIT_TESTS ?= 0
 ifeq ($(APP_UNIT_TESTS), 1)
 CFLAGS		+= -DAPP_UNIT_TESTS
 endif