Parse dcat license field

[jguo144]

Description

If the license field exists in the DCAT data.json file then try to map it to a license available in CKAN's license list.

[orca-security-us]

Orca Security Scan Summary

Status	Check	Issues by priority
Passed	Infrastructure as Code	0   0   0   0	View in Orca
Passed	Secrets	0   0   0   0	View in Orca
Passed	Vulnerabilities	0   0   0   0	View in Orca

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 55.55556% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 92.49%. Comparing base (ba43d5c) to head (ef23155).

Files	Patch %	Lines
ckanext/dcat/converters.py	55.55%	4 Missing ⚠️

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #40      +/-   ##
==========================================
- Coverage   92.54%   92.49%   -0.05%     
==========================================
  Files          38       38              
  Lines        7003     7012       +9     
==========================================
+ Hits         6481     6486       +5     
- Misses        522      526       +4     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[scastineyras]

LGTM
I saw the crd, was this field there before, and now we are adding it again, or it was never here?