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

---------

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

targets/f7/inc/stm32wb55_linker.h

@@ -0,0 +1,34 @@
+/**
+ * @file stm32wb55_linker.h
+ *
+ * Linker defined symbols. Used in various part of firmware to understand
+ * hardware boundaries.
+ * 
+ */
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern const void _stack_end; /**< end of stack */
+extern const void _stack_size; /**< stack size */
+
+extern const void _sidata; /**< data initial value start */
+extern const void _sdata; /**< data start */
+extern const void _edata; /**< data end */
+
+extern const void _sbss; /**< bss start */
+extern const void _ebss; /**< bss end */
+
+extern const void _sMB_MEM2; /**< RAM2a start */
+extern const void _eMB_MEM2; /**< RAM2a end */
+
+extern const void __heap_start__; /**< RAM1 Heap start */
+extern const void __heap_end__; /**< RAM1 Heap end */
+
+extern const void __free_flash_start__; /**< Free Flash space start */
+
+#ifdef __cplusplus
+}
+#endif