Merge #11413: [wallet] [rpc] sendtoaddress/sendmany: Add explicit feerate option

25dac9fa65 doc: add release notes for explicit fee estimators and bumpfee change (Karl-Johan Alm)
05227a3554 tests for bumpfee / estimate_modes (Karl-Johan Alm)
3404c1b753 policy: optional FeeEstimateMode param to CFeeRate::ToString (Karl-Johan Alm)
6fcf448430 rpc/wallet: add two explicit modes to estimate_mode (Karl-Johan Alm)
b188d80c2d MOVEONLY: Make FeeEstimateMode available to CFeeRate (Karl-Johan Alm)
5d1a411eb1 fees: add FeeModes doc helper function (Karl-Johan Alm)
91f6d2bc8f rpc/wallet: add conf_target as alias to confTarget in bumpfee (Karl-Johan Alm)
69158b41fc added CURRENCY_ATOM to express minimum indivisible unit (Karl-Johan Alm)

Pull request description:

  This lets users pick their own fees when using `sendtoaddress`/`sendmany` if they prefer this over the estimators.

ACKs for top commit:
  Sjors:
    re-utACK 25dac9fa65: rebased, more fancy C++,
  jonatack:
    ACK 25dac9fa65 I think this should be merged after all this time, even though it looks to me like there are needed follow-ups, fixes and test coverage to be added (see further down), which I don't mind helping out with, if wanted.
  fjahr:
    Code review ACK 25dac9fa65

Tree-SHA512: f31177e6cabf3187a43cdfe93477144f8e8385c7344613743cbbd16e8490d53ff5144aec7b9de6c9a65eb855b55e0f99d7f164dee4b6bf3cfea4dce51cf11d33

doc/release-notes-11413.md

@@ -0,0 +1,11 @@
+Updated or changed RPC
+----------------------
+
+The `bumpfee`, `fundrawtransaction`, `sendmany`, `sendtoaddress`, and `walletcreatefundedpsbt`
+RPC commands have been updated to include two new fee estimation methods "BTC/kB" and "sat/B".
+The target is the fee expressed explicitly in the given form. Note that use of this feature
+will trigger BIP 125 (replace-by-fee) opt-in.
+
+In addition, the `estimate_mode` parameter is now case insensitive for all of the above RPC commands.
+
+The `bumpfee` command now uses `conf_target` rather than `confTarget` in the options.