[fidl] Migrate error syntax to fitx::result
This change converts all the FIDL result union producing
methods/operators (`.Unwrap()`, `.value()`, `->`, `*`) to their
`fitx::result` producing equivalents (`.Unwrap_NEW()` and
`.value_NEW()`). Once the migration to the new methods is complete and
there are no remaining dependencies on the old methods, a follow-up
change will be submitted to remove the `_NEW()` suffixes.
Bug: 93988
Test: fx build; fx test; fx lsc presubmit
Change-Id: Ie6392ebffb2afef648d51dd16d1b8439505a0525
4 files changed
