[foreign-preview] RFR: 8280527: Move jdk.incubator.foreign to java.lang.foreign [v4]

[Maurizio Cimadamore]

On Thu, 27 Jan 2022 16:57:56 GMT, Julia Boes <jboes at openjdk.org> wrote:

>> To prepare for preview, this change removes the jdk.incubator.foreign module and moves the public classes to java.base/java.lang.foreign, implementation classes to java.base/jdk.internal.foreign respectively. 
>> 
>> While here, `SystemLookup` is replaced with the method `ClassLoader::findNative` and the methods in `MemoryHandles` are moved to `MethodHandles`. The `@PreviewFeature(feature=PreviewFeature.Feature.FOREIGN)` annotation and the `--enable-preview` flag are added were needed.
>
> Julia Boes has updated the pull request incrementally with one additional commit since the last revision:
> 
>    revert to static helper method for consistency

Looks good

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Marked as reviewed by mcimadamore (Committer).

PR: https://git.openjdk.java.net/panama-foreign/pull/633