Add "BOOLEAN" to type map of MSSQLToGCSOperator and fix incorrect BIT->INT conversion

[shahar1]

---

closes: #11874

In this PR, two problems are resolved:

1. "BOOLEAN" data type is added to MSSQLToGCSOperator type map.
2. Incorrect type conversion in the same operator, from BIT to INT, is resolved by explicitly specifying a sequence of bit fields in the MSSQL schema. Unfortunately, there is no other way for now to detect BIT data types beforehand - as the type ID received by the cursor is identical to INT (3).

^ Add meaningful description above

Read the Pull Request Guidelines for more information.
In case of fundamental code changes, an Airflow Improvement Proposal (AIP) is needed.
In case of a new dependency, check compliance with the ASF 3rd Party License Policy.
In case of backwards incompatible changes please leave a note in a newsfragment file, named {pr_number}.significant.rst or {issue_number}.significant.rst, in newsfragments.