feat: Fee Quantization Bands

[theborakompanioni]

Add quick selection for common maker fees settings on the Earn page.
Explain the reason and encourage users to use these (e.g. small info box when custom value is provided).

QUANT_REL = [2e-5, 5e-5, 1e-4, 2e-4, 5e-4, 1e-3, 2e-3, 5e-3, 1e-2, 2e-2, 5e-2, 1e-1]
                  # in percent: 0.002, 0.005, 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10
QUANT_ABS = [100, 200, 500, 1000, 2000, 5000, 10000]   # sats per slot

See "Fee Quantization Bands" on https://joinmarket-ng.sgn.space/
Full discussion: joinmarket-ng/joinmarket-ng#508