Enhance URL path handling in config.go and provider.go

[DharunKumar04]

This pull request updates the config.go and provider.go files to enhance URL path handling within the URL package. Specifically, the changes made are as follows:

config.go:

• Added constants for GITSuffix, APIMount, and GITMount to improve code readability.
• Minor code refactoring and cleanup for better maintainability.

provider.go:

• Implemented a JoinPath function to join path segments to a URL.
• Updated URL path handling to use the path.Join and ResolveReference methods for more robust and reliable path construction.
• Replaced p.uiURL.JoinPath with p.uiURL.ResolveReference to correctly join paths for the UI URL.

These changes aim to ensure consistent and correct URL path generation across the codebase, making it easier to maintain and extend in the future.

Please review the changes, and let me know if any further adjustments or improvements are needed. Your feedback is greatly appreciated!