RFR: 8336032: Enforce immutability of Lists used by ClassFile API

[Chen Liang]

In #20241, it's noted that `ClassFile.verify` can return a mix-and-match of mutable and immutable lists.

Though the mutability of the list returned by `verify` has no particular importance, as the mutable list is constructed on every call and does not mutate the models, there are a few scenarios that they matter. Since ClassFile API is designed with immutability in mind, we should change all lists in ClassFile API to be immutable.

Change summary:
- Critical scenarios where ClassFile API stores mutable objects:
  - `ClassSignature.typeParameters` - keeps user mutable list
  - `CompoundElement.elementList` - buffered models expose the underlying mutable list
  - `RuntimeInvisibleParameterAnnotationsAttribute`(and Visible) - keeps users' nest mutable lists in an immutable list
  - `StackMapFrameInfo.locals/stack` - keeps user mutable lists
- Optional scenarios to return immutable for good practice
  - `ClassFile.verify` - mutable for full verified results
  - `CompoundElement.elementList` - safe mutable for bound models
- Fail fast on user null `Attribute`s in `BoundAttribute.readAttributes` to prevent unmodifiable list containing null

I have also checked if we should stick with null-hostile `List.of` lists instead of `Collections.unmodifiableList` lists; we are using `unmodifiableList` (extensively in Signature parsing, for example) or other ad-hoc immutable lists, so it is somewhat impractical and not meaningful to enforce null-hostility. (See the list in JBS)

These use sites are too sporadic so I made no unit tests.

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Commit messages:
 - 8336032: Enforce immutability of Lists used by ClassFile API

Changes: https://git.openjdk.org/jdk/pull/20380/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20380&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336032
  Stats: 30 lines in 11 files changed: 17 ins; 1 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/20380.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20380/head:pull/20380

PR: https://git.openjdk.org/jdk/pull/20380