C8 capture support

[NotherNgineer]

Support for optionally saving Capture files in C8 format (converting from C16 to C8 as data is written to the file), and for reading C8 or C32 files during Replay/Playlist (automatically converting from C8/C32 to C16 as data is read from the file).

(A small part of enhancement request #1277)

[NotherNgineer]

A test version of the firmware with these changes is on Discord here:
https://discord.com/channels/719669764804444213/722101917135798312/1131674484030570607

[Brumi-2021]

Hi thanks 😊 for adding this nice feature !
I really wanted to have towards exploring to increase in future a good quality capture / replay at 1 MHz , 2Mhz .

I just evaluated quickly in capture / replay at 250/500 Khz some broadband FM in .c8/.c16 , and seems to work correctly .( at < = 500 Khz seems all ok )

I also tried to reproduce some large .c8 file 240 MB recorded with 2Mhz rate and found two issues :

1-) the second % bar reproduction status is only using low area 2 or 3 % and resets to zero and again same .
(That bug was there before your change . Gps simul App works well using all % progress reproduction bar)

2-) comparing the reproduction quality , GPS simul reproduces with less digital errrors , better quality . I guess that is due to that GPS simul has not activated waterfall , and therefore not M4 skipping . But it is a very good first step !

but really great 👍 job !!!

[NotherNgineer]

I changed this one back to a Draft so it won't get merged yet. (Don't hold up any potential 1.7.4 release for this one.)