[code-reflection] RFR: Ensure HAT executes with Babylon JDK images build

[Paul Sandoz]

HAT only executes correctly with a Babylon JDK exploded build, and fails with an images build.

We need to declare the runtime argument `--add-modules jdk.incubator.code`.

Also removed an `--add-exports` argument which no longer seems to be required.

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Commit messages:
 - Ensure HAT executes with Babylon JDK images build

Changes: https://git.openjdk.org/babylon/pull/684/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=684&range=00
  Stats: 5 lines in 4 files changed: 3 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/babylon/pull/684.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/684/head:pull/684

PR: https://git.openjdk.org/babylon/pull/684