Improve separation of scripting between EQL and SQL by delegating common
methods to QL. The context detection is determined based on the package
to avoid having repetitive class hierarchies.
The Painless whitelists have been improved so that the declaring class
is used instead of the inherited one.
Relates #53688
(cherry picked from commit 6d46033e736c64ac9255c5d6964600d2a931430a)
EQL: Add Substring function with Python semantics (#53688)
Does not reuse substring from SQL due to the difference in semantics and
the accepted arguments.
Currently it is missing full integration tests as, due to the usage of
scripting, requires an actual integration test against a proper cluster
(and likely its own QA project).
(cherry picked from commit f58680bad33d5ce4139157a69a4d9f5f286bc3c4)
Update CommonEqlRestTestCase code to simplify making changes as requested.
Update EqlActionIT to simplify the test code as requested.
Replace Jackson parser with XContent in EqlActionIT.
Whitelist more EQL tests specs that are now supported.