[foreign-memaccess+abi] RFR: Change classes into records and fix finality [v2]

[Per Minborg]

On Mon, 19 Sep 2022 13:58:53 GMT, Per Minborg <duke at openjdk.org> wrote:

>> This PR converts some of the regular classes into records. It also fixes some finality issues.
>> 
>> Note: Some methods with a very long method parameter list have their parameter list broken up into separate lines.
>
> Per Minborg has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Revert changes to VMStorage

Some of the internal classes that are not designed to be subclassed are marked as `final` to signal this fact. Admittedly, it is less important to keep internal classes non-final compared to classes in the public API. However, I think these changes merit the effort as the internal classes are likely to live for decades. 

Here is an article about finality: 

http://minborgsjavapot.blogspot.com/2021/12/why-general-inheritance-is-flawed-and.html

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PR: https://git.openjdk.org/panama-foreign/pull/725