[TECH DEBT]: Extract API calls to service file

[Pessina]

Currently our API calls are spread across the codebase and not typed.

The idea of this ticket it's create a service files where we will place the API calls, doing the following:

• Add typescript to the response
• Error handling
• Docs

I think this is a good ticket to discuss the approach, I extracted two API calls but we may have better solutions

Currently I'm placing the calls here: https://github.com/near/fast-auth-signer/blob/main/packages/near-fast-auth-signer/src/api/index.ts

cc: @esaminu

[Pessina]

createNEARAccount PR: https://github.com/near/fast-auth-signer/pull/131/files