Add correct lambda function argument name

Describe the bug In most of the places we are using it for the lambda function argument. it is not readable and not helps to understand what it represents.

Expected behavior Look for the below-mentioned test files and Replace it with the correct names

• PromotedStoryListViewModelTest (@Abhinavtdk )
• PromotedStoryViewModelTest (@jonathanalvares9009)
• TopicSummaryViewModelTest (@nskirkey)
• WelcomeViewModelTest (@ravi9607 )

Additional context Kotlin lambda function - https://kotlinlang.org/docs/lambdas.html#higher-order-functions

How to work on this issue Comment below “I want to work on [FILE_NAME]”, mention the file name from the above list you want to work on. Please work on only one file at a time.

Note: Don’t assign this issue to anyone as this issue should be done in a multiple PR fashion “single file, single PR”

[jonathanalvares9009]

I would like to work on PromotedStoryViewModelTest. Can I start with it?

[anandwana001]

I would like a bit more information on what would be correct as far as what we are renaming it to. Is there an objective correct name or is this something that we’re coming up with?

@nskirkey Taking an example from TopicSummaryViewModelTest https://github.com/oppia/oppia-android/blob/1711a35d59b3fed1a9a16903360b502e58bca8fb/app/src/sharedTest/java/org/oppia/android/app/home/TopicSummaryViewModelTest.kt#L99 It’s not readable just reading this line of code that what we are passing in the function, but if we look this code in the Android Studio we get the suggestions either we can use the suggestion or if you have anything better and more understandable term we can use, you can send a draft PR for review.

it.onActivity {
        setUpTestFragment(it)
}

it.onActivity { homeFragmentTestActivity ->
        setUpTestFragment(homeFragmentTestActivity)
}