Search for both databricks.exe and databricks binaries in windows (#517)

## Changes
<!-- Summary of your changes that are easy to understand -->

## Tests
<!-- 
How is this tested? Please see the checklist below and also describe any
other relevant tests
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- [x] `make test` run locally
- [x] `make fmt` applied
- [ ] relevant integration tests applied

databricks/sdk/credentials_provider.py

@@ -6,6 +6,7 @@
 import logging
 import os
 import pathlib
+import platform
 import subprocess
 import sys
 from datetime import datetime
@@ -473,11 +474,21 @@ def __init__(self, cfg: 'Config'):
             args += ['--account-id', cfg.account_id]
 
         cli_path = cfg.databricks_cli_path
+
+        # If the path is not specified look for "databricks" / "databricks.exe" in PATH.
         if not cli_path:
-            cli_path = 'databricks'
+            try:
+                # Try to find "databricks" in PATH
+                cli_path = self.__class__._find_executable("databricks")
+            except FileNotFoundError as e:
+                # If "databricks" is not found, try to find "databricks.exe" in PATH (Windows)
+                if platform.system() == "Windows":
+                    cli_path = self.__class__._find_executable("databricks.exe")
+                else:
+                    raise e
 
         # If the path is unqualified, look it up in PATH.
-        if cli_path.count("/") == 0:
+        elif cli_path.count("/") == 0:
             cli_path = self.__class__._find_executable(cli_path)
 
         super().__init__(cmd=[cli_path, *args],