Merge #15746: rpc: RPCHelpMan: Always name dictionary keys

<pre>Merge #15746: rpc: RPCHelpMan: Always name dictionary keys fa26eb5e8f rpc: RPCHelpMan: Always push_name when outer type is an object (MarcoFalke) fa652b229e rpc: Add some doxygen comments to utils (MarcoFalke) Pull request description: Fixes two issues reported in #15737: * &gt; I am very perplexed as to how the code I'm looking at is generating the help text I'm seeing So add documentation * &gt; This is a value for which a key is missing So always serialize the name of the dictionary key if the outer type is a dictionary ACKs for commit fa26eb: promag: Tested ACK fa26eb5. Tree-SHA512: b6f0cee1f1123d245d4902e8e113b5260cae7f2cb39c9bfb8893c5b0b33ffb6349ad05813d560d39a94ccf655399c05fcda15d9b0733e6bd696538fe0aca7021</pre>