[foreign-preview] RFR: 8280596: ScopedMemoryAccess_closeScope: remove exception parameter

[Julia Boes]

This change removes the trailing exception parameter in ScopedMemoryAccess_closeScope, which is now unused. 
(Plus some unrelated minimal doc cleanup that removes mentions of the old SymbolLookup class.)

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Commit messages:
 - some doc fixes
 - Merge branch 'foreign-preview' into close-scope-remove-param
 - initial commit

Changes: https://git.openjdk.java.net/panama-foreign/pull/637/files
 Webrev: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=637&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8280596
  Stats: 14 lines in 4 files changed: 0 ins; 3 del; 11 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/637.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/637/head:pull/637

PR: https://git.openjdk.java.net/panama-foreign/pull/637