feat: add overloads for file, file-pattern and url for from_source

[Oisin-M]

Description

Edit: done for all sources now. Should maybe move to .pyi files later.

Adds overloads to from_source so that one gets suggestions, type hints etc. when using the methods. Related to #989.

I've added this as a proof-of-concept for 3 sources using the docs here, gives the following suggestions:

Docs to be checked, but doesn't seem to link to autogenerated docs so I think we're fine there.

Contributor Declaration

By opening this pull request, I affirm the following:

• All authors agree to the Contributor License Agreement.
• The code follows the project's coding standards.
• I have performed self-review and added comments where needed.
• I have added or updated tests to verify that my changes are effective and functional.
• I have run all existing tests and confirmed they pass.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.44%. Comparing base (4633b7e) to head (ab280f8).
⚠️ Report is 3 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1035   +/-   ##
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  Coverage    82.44%   82.44%           
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  Files          237      237           
  Lines        16698    16698           
  Branches       808      808           
========================================
  Hits         13767    13767           
  Misses        2694     2694           
  Partials       237      237           

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