xds-compress2

lol

Signed-off-by: Tony Allen <tony@allen.gg>

xds-compress

mobile: Part 5: Update JNI usages with JniHelper (#30780)

This updates the following methods:
- `CallObjectMethod`
- `CallStaticObjectMethod`

This PR adds `[[nodiscard]]` to make sure we always assign the
`unique_ptr` into a variable when calling some JNI functions to avoid
any leaks. The `callObjectMethod` and `callStaticObjecMethod` from
`JniHelper` has been templatized to make them easy to use, especially
when casting from `jobject` to a different type. Some usages of
`Envoy::JNI::checkAndClear` have also been removed since they are no
longer necessary and we don't want to shallow the exceptions in most
cases.

Signed-off-by: Fredy Wijaya <fredyw@google.com>