LxmlEventHandler: support lxml Element or Tree as source

[tefra]

Support parsing from a subtree

import lxml

from xsdata.formats.dataclass.parsers import XmlParser
from xsdata.formats.dataclass.parsers.handlers import LxmlEventHandler

tree = lxml.etree.parse("/tmp/sample.xml")
parser = XmlParser(handler=LxmlEventHandler)
parser.parse(tree.find('.//{some}path'), SomeModel)

• Support element or tree in the lxml default handler
• Check if the native python xml has anything similar to lxml iterwalk api
• Tests

[codecov]

Codecov Report

Merging #531 (eae98a0) into master (5571268) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #531   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           95        95           
  Lines         7662      7664    +2     
  Branches      1325      1326    +1     
=========================================
+ Hits          7662      7664    +2     

Impacted Files	Coverage Δ
xsdata/formats/dataclass/parsers/handlers/lxml.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 5571268...eae98a0. Read the comment docs.

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[tefra]

For now this is an lxml only feature I am afraid.

[tefra]

Resolves #530