refactor: move Tool to a separate package; refactor serde

[anakin87]

Related Issues

Since we plan to introduce some subclasses of Tool (ComponentTool etc.), we thought of moving the dataclass into a dedicated package and make serialization/deserialization more flexible.

Proposed Changes:

• Move Tool to a new dedicated tools package.
• Refactor Tool serialization and deserialization to make it more flexible and include type information. (Same approach as POC in Tool from Component YAML serde POC haystack-experimental#164)

How did you test it?

CI, adapted tests

Notes for the reviewer

@dfokina your input here is necessary for the API reference docs.

• I removed the tool module from data_classes_api.
• I renamed tools_api (which previously contained components related to Tools, such as ToolInvoker) to tools_components_api.
• I put the new module tool (from tools package) into tools_api.

LMK if this makes sense.

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: and added ! in case the PR includes breaking changes.
• I documented my code
• I ran pre-commit hooks and fixed any issue

[vblagoje]

Looks good @anakin87

[dfokina]

I think it works well, thanks @anakin87 !

[coveralls]

Pull Request Test Coverage Report for Build 12687357337

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.006%) to 91.094%

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Totals
Change from base Build 12685847396:	0.006%
Covered Lines:	8653
Relevant Lines:	9499

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💛 - Coveralls