chore: use META-INF/licenses/$group/$artifact-$version/... folder for licenses

[vlsi]

See vlsi/vlsi-release-plugins@6122ea9

[vlsi]

Sample contents of the jar after updating license-gather plugin:

 Length   Method    Size  Cmpr    Date    Time   CRC-32   Name
--------  ------  ------- ---- ---------- ----- --------  ----
       0  Defl:N        2   0% 02-01-1980 00:00 00000000  META-INF/
   10454  Defl:N     2069  80% 02-01-1980 00:00 88964e44  META-INF/MANIFEST.MF
    1696  Defl:N      899  47% 02-01-1980 00:00 66179404  META-INF/LICENSE
       0  Defl:N        2   0% 02-01-1980 00:00 00000000  META-INF/licenses/
       0  Defl:N        2   0% 02-01-1980 00:00 00000000  META-INF/licenses/com.ongres.scram/
       0  Defl:N        2   0% 02-01-1980 00:00 00000000  META-INF/licenses/com.ongres.scram/client-2.1/
    1261  Defl:N      661  48% 02-01-1980 00:00 9c24427a  META-INF/licenses/com.ongres.scram/client-2.1/LICENSE
       0  Defl:N        2   0% 02-01-1980 00:00 00000000  META-INF/licenses/com.ongres.scram/common-2.1/
    1261  Defl:N      661  48% 02-01-1980 00:00 9c24427a  META-INF/licenses/com.ongres.scram/common-2.1/LICENSE
       0  Defl:N        2   0% 02-01-1980 00:00 00000000  META-INF/licenses/com.ongres.stringprep/
       0  Defl:N        2   0% 02-01-1980 00:00 00000000  META-INF/licenses/com.ongres.stringprep/saslprep-1.1/
    1261  Defl:N      660  48% 02-01-1980 00:00 9ced7c3a  META-INF/licenses/com.ongres.stringprep/saslprep-1.1/LICENSE
       0  Defl:N        2   0% 02-01-1980 00:00 00000000  META-INF/licenses/com.ongres.stringprep/stringprep-1.1/
    1261  Defl:N      660  48% 02-01-1980 00:00 9ced7c3a  META-INF/licenses/com.ongres.stringprep/stringprep-1.1/LICENSE
       0  Defl:N        2   0% 02-01-1980 00:00 00000000  META-INF/services/
      22  Defl:N       24  -9% 02-01-1980 00:00 b4e2de64  META-INF/services/java.sql.Driver
       0  Defl:N        2   0% 02-01-1980 00:00 00000000  org/
       0  Defl:N        2   0% 02-01-1980 00:00 00000000  org/postgresql/
     988  Defl:N      523  47% 02-01-1980 00:00 e798d869  org/postgresql/Driver$1.class
    3032  Defl:N     1683  45% 02-01-1980 00:00 6d5bacab  org/postgresql/Driver$ConnectThread.class
   17825  Defl:N     8538  52% 02-01-1980 00:00 11f41784  org/postgresql/Driver.class
...