RFR: 8341548: More concise use of classfile API

[Shaojin Wen]

java.base should provide best practices for Class File API

1. Use fluent coding style
2. Use aconst_null instead of oadConstant(null)
3. use astore intead of 'storeLocal(REFERENCE'
4. use aload instead of 'loadLocal(REFERENCE'
5. 'lload/lstore' instead of 'loadLocal(LONG)/storeLocal(LONG)'

-------------

Commit messages:
 - Update src/java.base/share/classes/java/lang/invoke/MethodHandleProxies.java
 - remove empty line
 - 'lload/lstore' instead of 'loadLocal(LONG)/storeLocal(LONG)''
 - MethodHandleProxies More concise use of classfile API
 - InnerClassLambdaMetafactory More concise use of classfile API
 - BindingSpecializer More concise use of classfile API
 - SwitchBootstraps more concise use of classfile API
 - More concise use of classfile API

Changes: https://git.openjdk.org/jdk/pull/21355/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21355&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8341548
  Stats: 326 lines in 5 files changed: 1 ins; 21 del; 304 mod
  Patch: https://git.openjdk.org/jdk/pull/21355.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21355/head:pull/21355

PR: https://git.openjdk.org/jdk/pull/21355