Fix Docker dependency issues #5332 and #5345

[glennmatthews]

Closes #5332

Closes #5345, but fix should be backported to ltm-1.6 too.

What's Changed

• In our Dockerfile, move the libxmlsec1-dev and libxmlsec1-openssl OS dependencies from the system-dev-dependencies stage to the system-dependencies stage so that they get included in the final Docker image to support SAML SSO integration. (This fixes Standard docker image includes dev dependencies #5332, which was a regression of Fixed dependencies required for saml support missing in final docker image #4282)
• In our Dockerfile, add poetry config installer.no-binary lxml to force lxml to be installed from source, fixing Random SAML SSO error - 405 method not allowed while login process #5345 (reference)
  • In the SSO setup documentation, add a note about using pip3 install --no-binary=lxml, similarly.
• In the Nautobot installation documentation, add a note about using pip3 install --no-binary=pyuwsgi since that was missing from the docs.

TODO

• Explanation of Change(s)
• Added change log fragment(s) (for more information see the documentation)
• n/a Attached Screenshots, Payload Example
• n/a Unit, Integration Tests
• Documentation Updates (when adding/changing features)
• n/a Example Plugin Updates (when adding/changing features)
• Outline Remaining Work, Constraints from Design