FLEX pager app (#2883)

* Add FLEX pager support

- Introduced a new FLEX configuration function in baseband_api.
- Added FLEX application view and associated UI elements.
- Implemented FLEX processing logic in proc_flex, including demodulation and message handling.
- Updated CMakeLists to include new FLEX source files and headers.
- Enhanced message system to support FLEX-specific messages and statistics.

This commit lays the groundwork for FLEX pager functionality, allowing for the reception and processing of FLEX messages.

* Fixed baseband and moved app to external with some other fixes.

* Format code

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Co-authored-by: RocketGod <57732082+RocketGod-git@users.noreply.github.com>

firmware/application/external/external.ld

@@ -86,6 +86,7 @@ MEMORY
     ram_external_app_bht_tx          (rwx) : org = 0xADED0000, len = 32k
     ram_external_app_morse_practice  (rwx) : org = 0xADEE0000, len = 32k
     ram_external_app_adult_toys_controller  (rwx) : org = 0xADEF0000, len = 32k
+    ram_external_app_flex_rx  (rwx) : org = 0xADF00000, len = 32k
 
 }
 
@@ -471,5 +472,10 @@ SECTIONS
         *(*ui*external_app*adult_toys_controller*);
     } > ram_external_app_adult_toys_controller
 
+    .external_app_flex_rx : ALIGN(4) SUBALIGN(4)
+    {
+        KEEP(*(.external_app.app_flex_rx.application_information));
+        *(*ui*external_app*flex_rx*);
+    } > ram_external_app_flex_rx    
 }