RFR: 8294972: jdk.jlink internal plugins are heavily using ASM

[Adam Sotona]

jdk.jlink internal plugins are heavily using ASM

This patch converts ASM calls to Classfile API.

Please review.
Thanks,
Adam

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Commit messages:
 - Merge branch 'master' into JDK-8294972-jlink-plugins
 - renamed variables in SystemModulesPlugin
 - 8294972: jdk.jlink internal plugins are heavily using ASM
 - removed obsolete javadoc from implementation classes
 - minor fix in CodeBuilder and added test cases to LDCTest
 - EntryMap::nextPowerOfTwo delegates to Long:numberOfLeadingZeros
 - fixed CodeBuilder:constantInstruction for -0.0d and -0.0f values and added test
 - Merge branch 'master' into JDK-8294982
 - fixed new lines at end of file
 - package jdk.internal.classfile.jdktypes moved to jdk.internal.classfile.java.lang.constant
 - ... and 180 more: https://git.openjdk.org/jdk/compare/cdcf5c1e...49c5bd59

Changes: https://git.openjdk.org/jdk/pull/12944/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12944&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8294972
  Stats: 1025 lines in 6 files changed: 215 ins; 300 del; 510 mod
  Patch: https://git.openjdk.org/jdk/pull/12944.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12944/head:pull/12944

PR: https://git.openjdk.org/jdk/pull/12944