[code-reflection] RFR: Enable sealing of an operation [v13]

[Mourad Abbay]

> Allow for an unbound operation to be sealed, causing it to be copied when we append it to a block builder.

Mourad Abbay has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 18 commits:

 - Merge branch 'code-reflection' into root-op-insertion
 - Apply review comments
 - Document Op.seal and Op.isSealed
 - Apply suggestions
 - Apply suggestions
 - Update TestFreezeOp as result of API change
 - Merge branch 'code-reflection' into root-op-insertion
   
   # Conflicts:
   #	src/jdk.incubator.code/share/classes/jdk/incubator/code/Op.java
   #	src/jdk.incubator.code/share/classes/jdk/incubator/code/internal/OpBuilder.java
 - Test that freezing an already bound op, throws
 - Test that structural quoted lambda are frozen
 - Update method Op.parentBlock to take into account frozen operations
 - ... and 8 more: https://git.openjdk.org/babylon/compare/cad3fdf3...4d220704

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Changes: https://git.openjdk.org/babylon/pull/425/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=425&range=12
  Stats: 149 lines in 5 files changed: 136 ins; 2 del; 11 mod
  Patch: https://git.openjdk.org/babylon/pull/425.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/425/head:pull/425

PR: https://git.openjdk.org/babylon/pull/425