Include branch-0.8 modifications back to main branch

[dacort]

What changes were proposed in this pull request?

• Exclude unnecessary Cat X licenses where possible. Per the incubator release vote, there were several Category X licenses in the binaries as well as a missing 3rd party license in the LICENSE file. This change skip tests when packaging, excludes several artifacts in the pom to prevent the licenses from being unnecessarily included, generates the THIRD-PARTY.txt file, and merges several variants of the Apache license.

How was this patch tested?

Building project during release process

Please review https://livy.incubator.apache.org/community/ before opening a pull request.

[codecov-commenter]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 67.99%. Comparing base (8b2e29f) to head (5ca81c7). :warning: Report is 17 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #429      +/-   ##
============================================
+ Coverage     65.48%   67.99%   +2.50%     
- Complexity      950      975      +25     
============================================
  Files           103      103              
  Lines          6062     6062              
  Branches        916      916              
============================================
+ Hits           3970     4122     +152     
+ Misses         1541     1353     -188     
- Partials        551      587      +36     

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[dacort]

@ksumit Done. :)