Additional RPC documentation fixes

[tomt1664]

Additional fixes for RPC documentation.

#	File	RPC	Issue
1	blockchain.cpp	getblockheader, getblock	"target" documented but never emitted
2	blockchain.cpp	getdescriptoractivity	"spend_vout" in docs vs "spend_vin" in code
3	blockchain.cpp	getblock	Typo "Uninforced" vs "Unenforced"
4	blockchain.cpp	scantxoutset	"asset" not optional
5	blockchain.cpp	getsidechaininfo	current_fedpeg_programs/current_fedpegscripts output order inverted
6	mining.cpp	getmininginfo	"next" not marked optional; absent on all signed-block chains
7	mining.cpp	getmininginfo	"signet_challenge"/"next" emit order inverted vs docs
8	mining.cpp	combineblocksigs	witnessScript declared optional but required for dynafed
9	mining.cpp	getcompactsketch	Return type STR should be STR_HEX
10	mining.cpp	getblocktemplate	"capabilities" pushed first, documented fourth
11	mining.cpp	getnewblockhex	Stale "Wallet keypool empty" error message
12	rawtransaction.cpp	decodepsbt	"fees" documented twice with conflicting types
13	rawtransaction.cpp	decodepsbt	"input_count"/"output_count" not marked optional
14	rawtransaction.cpp	getrawtransaction	Verbosity=0 return type STR should be STR_HEX
15	rawtransaction.cpp	combinerawtransaction	Return type STR should be STR_HEX
16	rawtransaction.cpp	rawblindrawtransaction	Return type STR should be STR_HEX
17	rawtransaction.cpp	rawblindrawtransaction	inputAmounts error says "input blind"
18	rawtransaction.cpp	rawblindrawtransaction	asset validation error says "asset blinds" not "asset ids"
19	rawtransaction.cpp	signrawtransactionwithkey	privatekey typed STR_HEX but is base58

Wallet RPC fixes:

#	File	RPC	Issue
1	coins.cpp	listunspent	"asset", "amountblinder", "assetblinder" not marked optional
2	coins.cpp	listunspent	"ancestorfees" typed STR_AMOUNT but code emits raw integer
3	coins.cpp	getreceivedbyaddress, getreceivedbylabel	include_immature_coinbase examples pass true as assetlabel
4	spend.cpp	walletcreatefundedpsbt	psbt_version implies configurability but only version 2 is accepted
5	spend.cpp	signrawtransactionwithwallet	amountcommitment prevtxs arg typed STR instead of STR_HEX
6	wallet.cpp	getwalletinfo	Balance OBJ fields document a fixed "bitcoin" key; code emits dynamic asset map
7	elements.cpp	createrawpegin	Result "hex" typed STR instead of STR_HEX
8	elements.cpp	sendtomainchain	bip32_counter result typed STR; should be NUM to match input arg type

[delta1]

Looks really good, just 2 things to fix up

[delta1]

ACK e5d02b9; tested locally