Add more interesting prometheus metrics

[MicaiahReid]

Once #552 is closed, we have an endpoint to serve prometheus metrics. We should add more metrics.

For these, we'd want to keep it to something that's actionable. Some ideas from claude:

• Transaction success/failure rate (counter, by status) — "why are 40% of my txs failing?"
• Transaction processing latency (histogram) — "is my program slow or is the RPC client slow?"
• RPC request rate by method (counter) — "is my client spamming getAccountInfo?"
• RPC request latency by method (histogram) — "which RPC calls are slow?"
• Remote account fetch latency (histogram) — "is mainnet cloning the bottleneck?"

[0xzrf]

hey @MicaiahReid
Can I pick this up?

[MicaiahReid]

I think @dvansari65 also wanted this one, y'all let me know who's going to do it, or you could split it up!

[0xzrf]

I think @dvansari65 can handle this
Just wanted to know

[dvansari65]

@0xzrf i am working on this, almost done