iOS ExternalActionViewModifierPlugin: make apply func open

[nancywu1]

exposing apply func so it can be overriden in ExternalWidgetPlugin

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  📦 Published PR as canary version: 0.9.2--canary.539.18398

  
  Try this version out locally by upgrading relevant packages to 0.9.2--canary.539.18398

[nancywu1]

/canary

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 89.57%. Comparing base (fb57765) to head (57070db).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #539 +/- ## ======================================= Coverage 89.57% 89.57% ======================================= Files 331 331 Lines 19718 19718 Branches 1949 1949 ======================================= Hits 17663 17663 Misses 2041 2041 Partials 14 14 ```

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[nancywu1]

/canary

[nancywu1]

/canary