[foreign-memaccess+abi] RFR: 8307253: Make FunctionDescriptor::toMethodType an instance method of Linker [v2]

[Maurizio Cimadamore]

> This patch moves `FunctionDescriptor::toMethodType` as an instance method of `Linker`. This allows linker implementations to be more opinionated on how the function descriptor -> method type conversion should behave.

Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:

  Revert changes.
  Fix javadoc and impl for FunctionDescriptor::toMethodType to allow sequence layouts.

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Changes:
  - all: https://git.openjdk.org/panama-foreign/pull/830/files
  - new: https://git.openjdk.org/panama-foreign/pull/830/files/083bf574..f5b4ef7a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=panama-foreign&pr=830&range=01
 - incr: https://webrevs.openjdk.org/?repo=panama-foreign&pr=830&range=00-01

  Stats: 159 lines in 9 files changed: 78 ins; 60 del; 21 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/830.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign.git pull/830/head:pull/830

PR: https://git.openjdk.org/panama-foreign/pull/830