[FL-2480] Use SysTick as the main OS timer (#1140)

* Use SysTick as OS tick timer
* Use LPTIM2 as tickless idle timer
* Remove dummy LPTIM2 IRQ handler
* Clean up clock init code
* Rename os timer to idle timer
* Advance hal ticks along with FreeRTOS's
* Improve SysTick control during tickless idle
* Improve idle timer precision
* Correct SysTick IRQ priority
* Main, FuriHal: move system startup to separate thread
* Minor code cleanup

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

firmware/targets/f7/furi_hal/furi_hal.c

@@ -10,6 +10,8 @@ void furi_hal_init_early() {
     furi_hal_clock_init_early();
     furi_hal_delay_init();
 
+    furi_hal_os_init();
+
     furi_hal_resources_init_early();
 
     furi_hal_spi_init_early();
@@ -75,9 +77,6 @@ void furi_hal_init() {
     furi_hal_bt_init();
     furi_hal_compress_icon_init();
 
-    // FreeRTOS glue
-    furi_hal_os_init();
-
     // FatFS driver initialization
     MX_FATFS_Init();
     FURI_LOG_I(TAG, "FATFS OK");