BLE fixes

[dhalbert]

(Same as #3848, but applied against 6.0.x instead of main; MagTag name fix not included because board is not in 6.0.x)

• Characteristic and descriptor max_lengths can be zero. Fixes BLE HID Keyboard not working in CircuitPython 6.0 #3746.
• Assure that start_scan() timeout is either zero or >= interval. This is a guess for this fix, but it coincides with working values reported in Low timeout values for BLERadio().start_scan() can lead to safe mode when calling BLERadio().connect() #3826. Fixes Low timeout values for BLERadio().start_scan() can lead to safe mode when calling BLERadio().connect() #3826.
• Assure that start_scan() max timeout is not too large for a uint16_t when passed to nRF SD. Fixes _bleio.Adapter.start_scan does not validate max timeout size #3340.
• Fixes small advertising interval values. Fix check and make sure it's at least 0.02001, to allow for rounding issues, as discussed in start_advertising interval does not accept the minimum 20ms value and may not range check correctly #2930. Fixes start_advertising interval does not accept the minimum 20ms value and may not range check correctly #2930.

Tested HID, and tested advertising scans with and without a timeout.

[tannewt]

Thank you!