fix: enhance error messages when source has extra/lacks double quotes

[aliehsaeedii]

Generalises the solution for issue#9243

Description

When performing DROP on a source name with a very special case of typo (typing source name mistakenly with/without double quotes), the error message is the same as when the source is not existing at all. This fix adds a Hint to the error message to make it more informative.

Testing done

Unit test manual testing

Reviewer checklist

• [ ] Ensure docs are updated if necessary. (eg. if a user visible feature is being added or changed).
• [ ] Ensure relevant issues are linked (description should include text like "Fixes #")

[aliehsaeedii]

@Gerrrr Do you please review this PR?