Remove TactilityC and Firmware subprojects (#638)

- Removed TactilityC, moved its symbols to existing modules and several new ones (pthread-module, c-symbols-module, cpp-symbols-module, posix-symbols-module, freertos-module).
- Removed Firmware subproject and moved main() into Tactility subproject.
- Strengthened application archive, path, version, stack-size, and device validation.
- Moved symbol resolution for elf_loader to app-esp32-module.
- Improved `struct Module` declarations and made module and symbol definitions in modules more consistent.
- Removed old http download code from Tactility subproject.
- Rename app-module's source files for consistency.
- Add missing pthread symbols.
- Kernel module symbols are now resolvable on all platforms.

TactilityKernel/include/tactility/module.h

@@ -13,6 +13,9 @@
 #endif
 
 #define DEFINE_MODULE_SYMBOL(symbol) { #symbol, (void*)&symbol }
+/** For an overloaded symbol (e.g. libc++/libstdc++'s float/double/long double math overloads),
+ * where a bare `&symbol` is ambiguous - `type` picks the overload to take the address of. */
+#define DEFINE_MODULE_SYMBOL_SIGNATURE(symbol, type) { #symbol, (void*)(type)&symbol }
 
 #ifdef __cplusplus
 extern "C" {