Play Framework

refactor(test): extract IntegrationTrustStore helper for WS HTTPS tests

Lift the JKS-from-PEM truststore builder out of WSAsyncFunctionalTest so
future WS-targeted integration tests can share the same wiring. The
helper transcodes testapp/certs/host.cert into a temp JKS (deleted on
JVM exit) and exposes the matching password as a constant, which is the
shape WSAsync wants — it reads ssl.keyStore / ssl.keyStorePassword from
Play.configuration and requires a JKS path, not raw PEM.

No behaviour change: ant integration-test still 29/29 with
WSAsyncFunctionalTest unchanged at 7 tests.

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