* Examples: remove unused context
* FuriHal: add simple ADC API
* Examples: add ADC example app
* FuriHal: add extended configuration options for ADC API
* FuriHal: add ADC clock configuration, fix calibration routine for single ended mode, new optimized parameters, documentation.
* FuriHal: add FuriHalAdcChannelTEMPSENSOR sampling time note
* FuriHal: update FuriHalAdcChannelVBAT description.
* FuriHal: use insomnia while ADC is acquired.
* Examples: cleanup example_adc a little bit
