Support resource leeway parameter when simulating Soroban transactions.

[Shaptic]

What

This adds an optional addlResources parameter to the Soroban RPC's simulateTransaction method which lets users specify an additional leeway for CPU instruction usage in their transaction simulation:

interface SimulationResources {
  cpuInstructions: number;
}

Why

The Soroban RPC server introduced this optional feature as part of the (pending) v20.1.0 (see stellar/stellar-cli#1131).

This additionally fixes #895.

[github-actions]

Size Change: +3.15 kB (0%)

Total Size: 11.4 MB

Filename	Size	Change
dist/stellar-sdk.js	6.3 MB	+1.92 kB (0%)
dist/stellar-sdk.min.js	5.07 MB	+1.23 kB (0%)

_{compressed-size-action}

[stellarsaur]

Thanks for the quick change! 💪