Play Framework

fix: forward conf jvm.memory + jmx.* to forked JVMs (PF-92)

Round out the 1.12 Python launcher parity audit started in d3c08a85d.
The launcher's java_cmd lifted four families of conf entries onto the
JVM command line; only javaagent.path and agentlib were addressed in
the first pass. This adds the remaining two:

- jvm.memory: whitespace-split into discrete JVM args. Conf value comes
  before extraJvmArgs so a user's -PjvmArgs="-Xmx4G" overrides under
  JVM last-wins semantics.
- jmx.port + jmx.hostname: emits the same 7-flag JMX agent setup the
  Python launcher did (ssl=false, authenticate=false, local.only=false).
  Only fires when both keys are set; defaults are insecure-by-default
  but match 1.12 verbatim — operators harden via -PjvmArgs if exposing
  JMX off-host.

Also wires confJvmArgs into spawnPlay so playStart and playRestart get
parity alongside playRun/playTest/playPrecompile/playEvolutions and
playAutotest. spawnPlay's existing extraJvmArgs slot is preserved and
runs after confJvmArgs.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>