[code-reflection] RFR: Review FieldLoadOp [v3]

[Mourad Abbay]

> Make sure FieldLoadOp is consistent with other reflective operations.

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

 - Delete unnecessary comment
 - Merge code-reflection branch into this branch
 - Reduce the number of FieldLoadOp constructors
 - Delete unnecessary comment
 - Add resultType param to fieldLoad factory methods

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Changes: https://git.openjdk.org/babylon/pull/19/files
 Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=19&range=02
  Stats: 81 lines in 3 files changed: 64 ins; 0 del; 17 mod
  Patch: https://git.openjdk.org/babylon/pull/19.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/19/head:pull/19

PR: https://git.openjdk.org/babylon/pull/19