RFR: Update code to use address target layouts

Mon Jan 30 17:45:32 UTC 2023

On Mon, 30 Jan 2023 17:38:54 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> This patch tweaks jextract to replace usages of `OfAddress.asUnbounded` with:
> 
> `withTargetLayout(sequenceLayout(JAVA_BYTE))`

Note: there are some failing tests (bitfields) due to the changes introduced by https://git.openjdk.org/panama-foreign/pull/766. We will deal with those in another PR.

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PR: https://git.openjdk.org/jextract/pull/100