soroban-rpc: Use External Soroban Crates

[stellarsaur]

What

Rather than building crates locally, this PR fetches published versions from crates.io instead.

Why

The soroban-tools repository should be responsible for building & publishing these crates.

[sreuland]

it's not in this change set, but the refs to rpc and cli repos in e2e.yml needs to now be udpated to ref this repo and wherever cli resides now(still soroban-tools?)

https://github.com/stellar/soroban-rpc/blob/rpc-prune/.github/workflows/e2e.yml#L93-L94

otherwise based on current e2e.yml config, it's passing based off code in soroban-tools not this repo

[stellarsaur]

it's not in this change set, but the refs to rpc and cli repos in e2e.yml needs to now be udpated to ref this repo and wherever cli resides now(still soroban-tools?)

https://github.com/stellar/soroban-rpc/blob/rpc-prune/.github/workflows/e2e.yml#L93-L94

otherwise based on current e2e.yml config, it's passing based off code in soroban-tools not this repo

Thanks for the reminder!

Please reference this PR moving forward. Closing this one as it's stale.