fix unzip pattern and strip_root should be used together

[jusito]

Changelog: Bugfix: Make possible to use pattern and strip_root at the same time for conan.tools.files.unzip().
Docs: Omit

fixes #14455

Found today that during archive extraction pattern and strip_root can't be used together. Same as in the related issue I would expect that pattern is applied before strip_root but actually they currently can't be used together at all.

• Refer to the issue that supports this Pull Request.
• If the issue has missing info, explain the purpose/use case/pain/need that covers this Pull Request.
  • no info required because expected behaviour restored
• I've read the Contributing guide.
• I've followed the PEP8 style guides for Python code.
• I've opened another PR in the Conan docs repo to the develop branch, documenting this one.
  • I guess this doesn't apply here?

[CLAassistant]

All committers have signed the CLA.

[franramirez688]

LGTM! Thanks a lot for the contribution @jusito

I just suggested a small detail in one of the unittests.