Code Cleanup: unused includes, useless checks, unused variables, etc... (#3696)

* Remove unnecessary checks
* Sublime: never insert missing headers
* Cleanup furi defines use
* Cleanup startup. Cleanup linker scripts. Explicitly define all interrupts hadlers, including uninmplemented one.
* Startup routine in C
* Drop assembler startup
* Move linker defines to stm32wb55_linker.h, cleanup naming, unify usage. Mpu: protect last 32b of main stack. Document various obscure things.
* Move furi_hal_switch documentation to appropriate place, use 0x0 for updater jump.
* UnitTests: move all temporary test files into tmp folder

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Co-authored-by: SG <who.just.the.doctor@gmail.com>

furi/core/memmgr_heap.c

@@ -39,6 +39,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <stm32wbxx.h>
+#include <stm32wb55_linker.h>
 #include <core/log.h>
 #include <core/common_defines.h>
 
@@ -63,8 +64,6 @@ task.h is included from an application file. */
 #define heapBITS_PER_BYTE ((size_t)8)
 
 /* Heap start end symbols provided by linker */
-extern const void __heap_start__;
-extern const void __heap_end__;
 uint8_t* ucHeap = (uint8_t*)&__heap_start__;
 
 /* Define the linked list structure.  This is used to link free blocks in order