Add support for Meshnology W12 and LR2021 Wrapper

[oltaco]

Add support for the Meshnology W12 board and a RadioLib wrapper for LR2021 with side-detector (multi-SF) support. Currently side detector config is not persisted to preferences.

The side detectors can be configured on repeater with set extra.sf x,y,z where x y and z are the extra spreading factors. Note that there are restrictions on what extra spreading factors are allowed.
From the LR2021 datasheet:

 Up to 4 Spreading Factors (SF) can be detected in parallel (main SF + 3 side detectors).
 The main SF (configured with SetLoraModulationParams) must be the smallest SF in normal Rx operation and the largest SF for CAD
operation.
 The header type is fixed by the main SF.
 If the BW is greater than 500kHz, only a maximum of two side detectors are allowed.
 If the main SF is 10, 11, or 12, only one side detector is allowed (maximum two SFs can be detected simultaneously).
 All SFs must be different; it is not possible to have two of the same SF in parallel.
 The difference between the Max SF and Min SF must be less than or equal to 4.

Note the #ifdef (USE_LR2021) lines in RadioLibWrappers.cpp, these are necessary because if you call startReceive on LR2021 when it is already in receive mode then the radio throws -706 repeatedly in loop until the next TX happens. This is due to differences in what RadioLib does in when setting the radio to StageMode(RX).