wallet/rpc: sendrawtransaction maxfeerate

Summary:

• test: Refactor vout fetches in rpc_rawtransaction
• wallet/rpc: add maxfeerate parameter to sendrawtransaction
• wallet/rpc: add maxfeerate parameter to testmempoolaccept

This is a backport of Core PR13541

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Subscribers: majcosta

Differential Revision: https://reviews.bitcoinabc.org/D6263