feat: rework RPC API dispatch_query

Summary

• test: use proc_sql_dispatch in tests

• refactor: use proc_sql_dispatch in cli::connect

• feat: rework RPC API dispatch_query

  • rename it to proc_sql_dispatch
  • modify args so that it's more suitable for public RPC API

Follow ups

• Create issues
• sbroad:
  • remove Context - sbroad#700 (closed)
  • remove structs that were used for args in proc_sql - sbroad#701
  • rename execute to proc_sql_execute - sbroad#702 (closed)
• tarantool-module
  • proc should allow skipping optional arguments - tarantool-module#205
  • proc should allow doc comments for fn parameters - tarantool-module#204 (closed)

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• Close #608 (closed)
• Cherry-pick to: none
• Docs follow-up: docs#288 (closed)