App hub and more (#383)

- Added `AppHub` app
- Added `AppHubDetails` app
- Added `cJSON` dependency
- Renamed `AppSim` module to `FirmwareSim`
- Added extra `tt::app::alertdialg::start()`
- Renamed `addApp()`, `removeApp()`, `findAppById()` and `getApps()` to `addAppManifest()`, `removeAppManifest()`, `findAppManifestById()` and `getAppManifests()`
- Added `tt::lvgl::toolbar_clear_actions()`
- Added `tt::network::EspHttpClient` as a thread-safe wrapper around `esp_http_client`
- Added `tt::network::http::download()` to download files
- Added `tt::network::ntp::isSynced()`
- When time is synced, the timestamp is stored in NVS flash. On boot, it is restored. This helps SSL connections when doing a quick reset: when WiFi reconnects, the user doesn't have to wait for NTP sync before SSL works.
- Added `tt::json::Reader` as a `cJSON` wrapper
- Added `int64_t` support for `Preferences`
- Added `int64_t` support for `Bundle`
- Added dependencies: `cJSON`, `esp-tls`
- When time is synced via NTP, disable time sync.
- Added docs to 'tt::file::` functions
- Added `tt::string::join()` that works with `std::vector<const char*>`
- Fixed `tt::file::getLastPathSegment()` for the scenario when a path was passed with only a single segment
- Set `CONFIG_ESP_MAIN_TASK_STACK_SIZE=5120` (from about 3k) for all boards
- Set `CONFIG_MBEDTLS_SSL_PROTO_TLS1_3=y` for all boards

.gitmodules

@@ -13,3 +13,6 @@
 [submodule "Libraries/minitar/minitar"]
 	path = Libraries/minitar/minitar
 	url = https://github.com/ByteWelder/minitar.git
+[submodule "Libraries/cJSON/cJSON"]
+	path = Libraries/cJSON/cJSON
+	url = git@github.com:DaveGamble/cJSON.git