RFR: 8258715: [JVMCI] separate JVMCI code install timers for CompileBroker and hosted compilations

[Doug Simon]

Currently, a single timer is used for timing JVMCI based installation of code into the code cache. This makes it impossible to work out how much time is for compilations requested by the CompileBroker and how much is for "hosted" compilations (i.e. requested from the JVMCI Java API). This PR separates out timers for each of these compilation types.

Here's an example of how the JVMCI section in the output for `-XX:+CITime` now looks:
    JVMCI CompileBroker Time:
       Compile:         15.794 s
       Install Code:     0.182 s

    JVMCI Hosted Time:
       Install Code:     0.035 s

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Commit messages:
 - use separate code installation timers for hosted vs CompileBroker JVMCI compilations

Changes: https://git.openjdk.java.net/jdk/pull/1847/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1847&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8258715
  Stats: 42 lines in 4 files changed: 20 ins; 9 del; 13 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1847.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1847/head:pull/1847

PR: https://git.openjdk.java.net/jdk/pull/1847