[foreign-memaccess+abi] RFR: 8305087: MemoryLayout API checks should be more eager

[Maurizio Cimadamore]

This patch adds eager check on construction of sequence and group layouts. More specifically:

* sequenceLayout(L) is well-formed iff L.bitAlignment() <= L.bitSize()
* groupLayout(L1, … Ln) is well-formed iff for-each 1..n, offset(Li) % Li.bitAlignment() == 0

Moreover, this patch also validates the alignment parameter to calls of `MemoryLayout::withBitAlignment` on sequence and group layouts:

* sequenceLayout(L).withBitAlignment(a) is well-formed iff L.bitAlignment() <= a
* groupLayout(L1, ..., Ln).withBitAlignment(a) is well-formed iff max(L1.bitAlignment(), ...,  Ln.bitAlignment()) <= a

These checks prevent bad layouts from being constructed (either with factories, or with bad calls to `withBitAlignment`), w/o restricting the expressiveness of the memory layout API.
Moreover, since all layouts are now well-formed by construction, we no longer need lazy checks when creating a deferefence var handle.

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Commit messages:
 - Initial push

Changes: https://git.openjdk.org/panama-foreign/pull/824/files
 Webrev: https://webrevs.openjdk.org/?repo=panama-foreign&pr=824&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8305087
  Stats: 238 lines in 17 files changed: 73 ins; 147 del; 18 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/824.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign.git pull/824/head:pull/824

PR: https://git.openjdk.org/panama-foreign/pull/824