[foreign-memaccess+abi] RFR: Split Stream operations, fix final and class properties

[Maurizio Cimadamore]

On Mon, 19 Sep 2022 12:20:41 GMT, Per Minborg <duke at openjdk.org> wrote:

> This PR splits Stream operations into separate lines, and fixes some `final` and class issues.
> 
> Some smaller issues are also fixed not related to the above.

This changeset seems borderline "too broad" as it's fixing a host of different, unrelated issues. That said, willing to approve given that most of the changes seem relatively cosmetic. (again, for `final` classes in non-exported impl, as well as for adding default private constructor _always_ I think that's matter of style, and is definitively not applied to the JDK as a whole - but I'm willing to go with it).

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Marked as reviewed by mcimadamore (Committer).

PR: https://git.openjdk.org/panama-foreign/pull/724