[MainUI] - flags to hide RApp section and some settings

[schmurtzm]

Currently we edit MainUI binary to create 4 different binaries :

2 for the MM and 2 for the MM+.
For each we change the settings sections :

MMP :
Hide Audio fix page (fixit.png menu)
Hide Factory reset page (icon-factory-reset-48.png menu)
Hide Keys map (icon-key-setting-48 menu)
Hide Themes (icon-theme. png menu)
Hide Harware test (last icon-device-info-48.png menu)
Hide Battery icon -- Onion compliance
Needs to adress the battery png to .batt-perc.png, at every battery state
brightness glitch fix
(/sys/class/pwm/pwmchip0/pwm0/duty_cycle 1 to /dev/null)

MM :
All of the above +
Hide Wifi (icon-setting-wifi.png menu)
Device name is changed to MY283 in the informations page

Then we decline the MM and MMP version in clean version : without the expert tab (ic-retroarch-n.png)

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Request :
A flag or a config file to hide expert tab (= RApp tab) could be nice.
Same for the stuffs to hide : if we could select what we want to display in settings it could help.