[PECOBLR-762] Make U2M work independent to that of java sdk (#954)

## Description
- We have had issues with making Azure U2M work in the long term, this
PR is to fix these issues in the next release.
- In this PR we have replicated the simple U2M flow added in our other
OSS drivers.

## Testing
- Added unit tests to maintain coverage.
- Tested manually using Auth_Flow=2 with adb host.
- Note that one of our customer also tested this out and says it is
working for them too.

## Additional Notes to the Reviewer
- This ticket will decide the future fate of placement of the Azure U2M
auth class : https://databricks.atlassian.net/browse/PECOBLR-762

Author: samikshya-db

NEXT_CHANGELOG.md

@@ -15,6 +15,7 @@
 - Databricks SDK dependency upgraded to latest version 0.60.0
 
 ### Fixed
+- Integrated Azure U2M flow into driver for improved stability.
 - Fixed `ResultSet.getString` for Boolean columns in Metadata result set.
 ---
 *Note: When making changes, please add your change under the appropriate section with a brief description.* 

src/main/java/com/databricks/jdbc/api/impl/DatabricksConnectionContext.java

@@ -215,6 +215,11 @@ public String getHostUrl() throws DatabricksParsingException {
     }
   }
 
+  @Override
+  public String getHost() {
+    return this.host;
+  }
+
   @Override
   public IDatabricksComputeResource getComputeResource() {
     return computeResource;

src/main/java/com/databricks/jdbc/api/internal/IDatabricksConnectionContext.java

@@ -17,6 +17,13 @@ public interface IDatabricksConnectionContext {
    */
   String getHostUrl() throws DatabricksParsingException;
 
+  /**
+   * Returns just the host parsed from JDBC connection. Note : this is not the url.
+   *
+   * @return Databricks host
+   */
+  String getHost();
+
   /**
    * Returns warehouse-Id as parsed from JDBC connection Url
    *