RFR: 8357220: Introduce a BSMAttributeEntry struct [v5]

[Johan Sjölen]

> Hi,
> 
>  The constant pool currently has a lot of methods specific to extracting parts of the operands array. What this array actually is, is a sequence of bootstrap method attribute entries, where each entry has the following components:
> 
> ```c++
> struct BSMAE {
>   u2 bootstrap_method_index;
>   u2 argument_count;
>   u2 arguments[argument_count];
> }
> 
> 
> We can removes some of these operands array specific methods, and instead allows you to extract BSMAttributeEntrys which you can then use to extract its piece wise components. This makes for a nicer interface, and a bit easier to come into as a reader of the code, as it more closely mirrors the JVMS. 
> 
> Please consider!
> 
> Testing: Currently GHA, running tier1-tier3

Johan Sjölen has updated the pull request incrementally with two additional commits since the last revision:

 - Matias's comments
 - Apply Sergei's comments

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/25298/files
  - new: https://git.openjdk.org/jdk/pull/25298/files/1c7484d7..af3caa9b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25298&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25298&range=03-04

  Stats: 17 lines in 4 files changed: 6 ins; 1 del; 10 mod
  Patch: https://git.openjdk.org/jdk/pull/25298.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25298/head:pull/25298

PR: https://git.openjdk.org/jdk/pull/25298