Feature Request: feePreference should have minFeeRate and maxFeeRate

[junderw]

feePreference.minFeeRate if the estimate of feeRate is below this, set the feeRate to this. (this is kind of an extension of explicitFeeRate)

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feePreference.maxFeeRate if the estimate of feeRate is above this, return error code.

I know there are probably sanity checks on bitcoind, NBitcoin, NBX, etc etc where it will throw error if fee are > 100000 sat/vByte (BitcoinJS also has a sanity check too)

But it would be nice to have a configurable sanity check.