Add config option to change GO for executing multi-line query

Sometimes users want the ability to choose a different indicator for when to execute a multi-line query. Adding a config option to allow a user to change "GO" to ";" for example could be a common use case for someone using both pgcli/mycli with mssql-cli

No file, test, or entry point is identified in the issue. Start by locating the multi-line query execution logic and the existing configuration handling in mssql-cli, then trace how the current GO indicator is recognized. Done means users can configure a different indicator, such as a semicolon, without changing the default behavior.

Written by the indexing model from the issue text.