CLI onboarding cannot upload configuration files to a volume in Databricks (Windows)

[prvasilev]

When trying to onboard config files, those are not uploaded as there is a '' prepended to the windows path which makes it invalid.

dlt-meta/src/cli.py:
line 460

Then
Line 167 def copy_to_uc_volume(self, src, dst):
removes only 'file:' which leaves the path in this example state: /C:\projects\dlt-meta\conf\

Onboarding silently completes, here's debug using the CLI

databricks labs dlt-meta onboard -p dbx-workspace --debug

[ravi-databricks]

@prvasilev please test fix in issue_251 branch!