* add a little Stash utility.
* add radio state RAII helper.
* first part of radio_state changes
* add radio_state_ to rest of apps
* fix freq_step and format
* fix unused ui_sigfrx: corrected sample rate, added back freq setting
When starting the app, actual tx gain is 47 while the ui shows 10. "Increasing" gain to 11 takes effect, reducing actual gain as displayed in UI. This change makes the UI gain value consistent with actual tx gain.
* Use receiver/transmitter models everywhere
* Run formatter
* Fix a copy-paste bug, make transmitter_model actually set tx_gain.
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Co-authored-by: kallanreed <kallanreed@outlook.com>