Thread, Timer and flash.sh improvements (#165)

- Various improvements to Thread and Timer:
  - Remove "mark as static" option as it is unused
  - Implemented core pinning for ESP32 platforms
  - Use `TickType_t` consistently (instead of `uint32_t`)
  - Use `enum class` instead of `enum`
- Fix for `flash.sh` not working when using `pip` to install `esptool`

Boards/M5stackCoreS3/Source/InitLvgl.cpp

@@ -12,7 +12,7 @@
 
 bool initLvgl() {
     const lvgl_port_cfg_t lvgl_cfg = {
-        .task_priority = tt::THREAD_PRIORITY_RENDER,
+        .task_priority = static_cast<UBaseType_t>(tt::THREAD_PRIORITY_RENDER),
         .task_stack = CORE2_LVGL_TASK_STACK_DEPTH,
         .task_affinity = -1, // core pinning
         .task_max_sleep_ms = 500,