[Java] Bump Log4j2 to completely remove lookups (ray-project#21081)

As per the 2.16.0 release of Lo4j2, Lookup support is removed 🎉 
https://logging.apache.org/log4j/2.x/changes-report.html#a2.16.0

[Datasets] Last-mile preprocessing docs. (ray-project#20712)

Datasets docs for last-mile preprocessing, particularly geared towards ML ingest. This gives groupby, aggregations, and random shuffling examples in the overview page (not present previously), adds some concreteness to our last-mile preprocessing positioning, and provides some preprocessing recipes for a few common transformations.

Revert change to set debug info to -g1 (ray-project#19900)

Fix windows build environment breakage (ray-project#19019)

Fix windows build environment breakage (ray-project#19019)

[dashboard] Don't start dashboard agent when missing dependencies (ra…

…y-project#17966)

LINT changes.

fall back to manual pin version

fall back to manual pin version

change to ray version 1.5.0