wallet+chain: add new APIs GetPeerInfo, GetBlockChainInfo, and RawRequest to chain interface

[mohamedawnallah]

Description

In this commit, we add new APIs to chain interface used across btcd, neutrino, and bitcoind chain backends. The new APIs are GetPeerInfo, GetBlockChainInfo, and RawRequest.

Addresses part of lightningnetwork/lnd#7951.
Dependent PR lightningnetwork/lnd#9435.

Motivation and Context

The motivation behind adding those APIs is to easier the process of unifying RPC connection creations across chain backends as part of LND Daemon.

[Roasbeef]

Approved CI.

[mohamedawnallah]

It looks like approval is required whenever an updated commit is submitted. Additionally, it doesn’t seem to be configured to trigger against the master branch in the forked repository.

I'm also unsure about the linting process when running make lint locally. For example, I'm encountering linting issues for code blocks I haven’t modified, such as FilterBlocks and handler:

chain/btcd.go:316: Function 'FilterBlocks' is too long (77 > 60) (funlen)
func (c *BtcdClient) FilterBlocks(
chain/btcd.go:496: Function 'handler' is too long (72 > 60) (funlen)
func (c *BtcdClient) handler() {
rpc/legacyrpc/methods.go:974: Function 'help' is too long (78 > 60) (funlen)
func help(icmd interface{}, _ *wallet.Wallet,
rpc/legacyrpc/methods.go:1593: Function 'signRawTransaction' has too many statements (86 > 40) (funlen)
...

EDIT:
How am I supposed to move this PR forward? The linter is requiring considerable code refactoring of the FilterBlocks, handler, and help functions after modifying their signatures. However, these refactoring changes are unrelated to the PR's original purpose. What's the best way to handle this situation?