[foreign-memaccess+abi] RFR: added get/set-AtIndex methods for byte, boolean [v2]

[RedIODev]

> This PR adds the left out getAtIndex and setAtIndex methods for byte and boolean to java.lang.foreign.MemorySegment.java

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

  added tests to TestMemoryAccessInstance

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Changes:
  - all: https://git.openjdk.org/panama-foreign/pull/747/files
  - new: https://git.openjdk.org/panama-foreign/pull/747/files/111a2eb4..1a7fd368

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=panama-foreign&pr=747&range=01
 - incr: https://webrevs.openjdk.org/?repo=panama-foreign&pr=747&range=00-01

  Stats: 8 lines in 1 file changed: 8 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/747.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign pull/747/head:pull/747

PR: https://git.openjdk.org/panama-foreign/pull/747