feat(sdk): add validation utils, update client, barrel, and README (#…#256

Tinna23 merged 1 commit intoStellarCommons:mainStellarCommons/Stellar-Explain:mainfrom

TomikeDS:feat/sdk-utils-client-barrel-readmeTomikeDS/Stellar-Explain:feat/sdk-utils-client-barrel-readmeCopy head branch name to clipboard