Refactor sync checks

[buffrr]

This PR introduces a few improvements to sync checks.

1. If spaces tip > the rpc endpoint's tip, it waits for the node to sync. This can happen if a user starts spaces but the Bitcoin node is still syncing.
2. Add progress to getserverinfo and getwalletinfo.
3. Add --bitcoin-rpc-light option to indicate that we're connecting a light-ish style node.
4. A few other clean ups

[randomlogin]

Pulled the new version, got the following problems:

1. Apparently waiting for a bitcoin node to sync does not cover all possible cases (process exits after the error message).

$ spaced --block-index --chain testnet4 --bitcoin-rpc-user test --bitcoin-rpc-password test 
[2025-04-22T12:29:16Z ERROR spaced] Could not retrieve activation block at height 50000: RPC: -28:Loading block index…

2. Cannot run on testnet4 properly (I had used completely the same command to start spaced before I pulled the new version and it worked):

$ spaced --block-index --chain testnet4 --bitcoin-rpc-user test --bitcoin-rpc-password test 
[2025-04-22T12:27:18Z INFO  spaces_client::rpc] Listening at 127.0.0.1:7224
[2025-04-22T12:27:18Z INFO  spaces_client::rpc] Listening at [::1]:7224
[2025-04-22T12:27:18Z INFO  spaces_client::sync] Start block=00000000248a42f7934cced05782fc38ffd085f325ab3a06629347280efcd288 height=78804
[2025-04-22T12:27:18Z WARN  spaces_client::source] Invalid chain from connected rpc node - expected test, got testnet4
[2025-04-22T12:27:19Z WARN  spaces_client::source] Invalid chain from connected rpc node - expected test, got testnet4
[2025-04-22T12:27:20Z WARN  spaces_client::source] Invalid chain from connected rpc node - expected test, got testnet4
[2025-04-22T12:27:21Z WARN  spaces_client::source] Invalid chain from connected rpc node - expected test, got testnet4
[2025-04-22T12:27:22Z WARN  spaces_client::source] Invalid chain from connected rpc node - expected test, got testnet4