Tolerate trailing slash

[mgyucht]

What changes are proposed in this pull request?

A recent refactor of U2M logic to the SDK introduced a small bug where a hostname with a trailing slash would be rejected when using databricks auth login, e.g. databricks auth login --host https://myworkspace.cloud.databricks.com/. This happens because AccountOAuthArgument and WorkspaceOAuthArgument both validate that the provided host does not have a trailing slash. Instead, we can tolerate hostnames ending with a slash by using the CanonicalHostName() method of Config to normalize the hostname, removing the unneeded trailing slash before passing the normalized hostname to U2M auth components. I have made a similar fix to getOidcEndpoints.

How is this tested?

Unit tests are added to verify that getOauthArgument on Config works with normalized hostnames, and same for getOidcEndpoints.

[github-actions]

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Trigger:
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Inputs:

• PR number: 1211
• Commit SHA: 064d162a13d7d2810fe4d70b795e0f06a263a38e

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