Merge bitcoin/bitcoin#25412: rest: add /deploymentinfo endpoint

a8250e30f1 doc: add release note about `/rest/deploymentinfo` (brunoerg)
5c96020024 doc: add `/deploymentinfo` in REST-interface (brunoerg)
3e44bee08e test: add coverage for `/rest/deploymentinfo` (brunoerg)
91497031cb rest: add `/deploymentinfo` (brunoerg)

Pull request description:

  #23508 added a new RPC named `getdeploymentinfo`, it moved the softfork section from `getblockchaininfo` into this new one. In the REST interface, we have an endpoint named`/rest/chaininfo.json` (which refers to `getblockchaininfo`), so, this PR adds a new REST endpoint named `/deploymentinfo` which refers to `getdeploymentinfo`.

  You can use it by passing a block hash, e.g: '/rest/deploymentinfo/<BLOCKHASH>.json' or you can use it without passing a block hash to get the 'deploymentinfo' for the last block.

ACKs for top commit:
  jonatack:
    re-ACK a8250e30f1 rebase-only since my last review at c65f82bb
  achow101:
    ACK a8250e30f1
  stickies-v:
    re-ACK a8250e30f1

Tree-SHA512: 0735183b6828d51a72ed0e2be5a09b314ac4693f548982c6e9adaa0ef07a55aa428d3b2d1b1de70b83169811a663a8624b686166e5797f624dcc00178b9796e6

doc/REST-interface.md

@@ -86,6 +86,15 @@ Returns various state info regarding block chain processing.
 Only supports JSON as output format.
 Refer to the `getblockchaininfo` RPC help for details.
 
+#### Deployment info
+`GET /rest/deploymentinfo.json`
+`GET /rest/deploymentinfo/<BLOCKHASH>.json`
+
+Returns an object containing various state info regarding deployments of
+consensus changes at the current chain tip, or at <BLOCKHASH> if provided.
+Only supports JSON as output format.
+Refer to the `getdeploymentinfo` RPC help for details.
+
 #### Query UTXO set
 - `GET /rest/getutxos/<TXID>-<N>/<TXID>-<N>/.../<TXID>-<N>.<bin|hex|json>`
 - `GET /rest/getutxos/checkmempool/<TXID>-<N>/<TXID>-<N>/.../<TXID>-<N>.<bin|hex|json>`