Apply fallback availability logic to beta information

[sofiaromorales]

Bug/issue #, if applicable: 127227456

Summary

Apply fallback availability logic to beta information.

For platforms that have a fallback platform, copy the availability information passed through the CLI, including the isBeta value.

The fallback platform logic works correctly for availability information passed through the SGFs but does not apply to availability information passed through the --platform CLI option. This inconsistency caused unexpected behavior. For instance, a symbol would copy the version from iOS, which is also marked as beta, and display it as available for both iOS and iPadOS, but only as beta for iOS.

This PR aims to fix this by also adding the same fallback mechanism to the information about the current release of a platform passed through the CLI.

Dependencies

N/A.

Testing

Steps:

1. Download the attached catalog.
2. Run `docc preview --platform name=iOS,version=16.0.0,beta=true
3. Assert that iPadOS and Catalyst are marked as beta

Availability.docc.zip

Checklist

Make sure you check off the following items. If they cannot be completed, provide a reason.

• Added tests
• Ran the ./bin/test script and it succeeded`
• Updated documentation if necessary

[d-ronnqvist]

Is there a reason why displayName is used on the key but rawValue is used on the value (both are PlatformName elements)?

Also, this can be written simpler using a regular for loop that binds the key and values to separate meaningful names. If you want you can also move the if statement into a where clause on the loop

Suggested change

	DefaultAvailability.fallbackPlatforms.forEach { fallbackPlatform in
	if (!currentPlatforms.keys.contains(fallbackPlatform.key.displayName)) {
	currentPlatforms[fallbackPlatform.key.displayName] = currentPlatforms[fallbackPlatform.value.rawValue]
	}
	}
	for (platform, fallbackPlatform) in DefaultAvailability.fallbackPlatforms where currentPlatforms[platform.displayName] == nil {
	currentPlatforms[platform.displayName] = currentPlatforms[fallbackPlatform.rawValue]
	}

[d-ronnqvist]

For clarification, there are two pieces to my comment above:

• A question if there's a potential bug with using .displayName for one of the platforms and .rawValue for the other
• A non-blocking style suggestions about using a regular loop and using contextually relevant variable names instead of "key" and "value".

[sofiaromorales]

I don't remember if the initial choice of using rawValue instead of displayName was intentional, but I don't think it makes a difference since in practice both will be the same (iOS).

However, after reviewing it, I decided to change it to displayName since it has the raw value as fallback and looks more consistent with the rest of the code.

self.displayName = displayName ?? rawValue

I updated the commit with the changes.

[d-ronnqvist]

LGTM

[patshaughnessy]

Looks good to me

[sofiaromorales]

@swift-ci please test