feat: support single metadata dictionary in TikaDocumentConverter

[ZanSara]

Related Issues

• related to Input parameter meta in FileTypeRouter #6392

Proposed Changes:

Adds support for single metadata dictionary input in TikaDocumentConverter. In this way, additional metadata can be added to all files processed by this component even when the length of the list of sources is unknown.

How did you test it?

Added tests and run locally.

Notes for the reviewer

See the linked issue and this discussion for context.

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.
• I documented my code
• I ran pre-commit hooks and fixed any issue

[coveralls]

Pull Request Test Coverage Report for Build 7448338237

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.01%) to 87.365%

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Totals
Change from base Build 7446805988:	0.01%
Covered Lines:	4052
Relevant Lines:	4638

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💛 - Coveralls

[anakin87]

It looks good.

I left two small comments about tests...