RFR: JDK-8303646: Add possibility to lookup ResolvedJavaType from jclass.

[Tomáš Zezula]

This pull request adds a `jdk.vm.ci.hotspot.HotSpotJVMCIRuntime#asResolvedJavaType(long hotspot_jclass_value)` method, which converts  a HotSpot heap JNI `hotspot_jclass_value` to a `jdk.vm.ci.meta.ResolvedJavaType`.

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Commit messages:
 - JDK-8303646: Add possibility to lookup ResolvedJavaType from HotSpot heap JNI jclass.

Changes: https://git.openjdk.org/jdk/pull/12878/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12878&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303646
  Stats: 42 lines in 3 files changed: 42 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/12878.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12878/head:pull/12878

PR: https://git.openjdk.org/jdk/pull/12878