[action][app_store_build_number] remove all instances of is_string in options and use type

[crazymanish]

Checklist

• I've run bundle exec rspec from the root directory to see all new and existing tests pass
• I've followed the fastlane code style and run bundle exec rubocop -a to ensure the code style is valid
• I've read the Contribution Guidelines
• I've updated the documentation if necessary.

Motivation and Context

• is_string is slowly being replaced by type to make the docs clearer, options safer, and Swift generation more correct.
• This PR does this for only app_store_build_number action.

Description

• Remove is_string from Boolean params and added type: Boolean
• Added missing unit-tests

Testing Steps

• No functionality changed, all existing/new unit tests should pass.

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[joshdholtz]

@googlebot I consent.

[joshdholtz]

Another great one! Thank you 😊

[fastlane-bot]

Congratulations! 🎉 This was released as part of fastlane 2.185.0 🚀