Get the app version name from BuildConfig instead of PackageManager for UserAgent

[aafanasev]

Description

ClientConfigurator class is in the app module. It has access to BuildConfig which contains VERSION_NAME. No need to use PackageManager.

Checklist

• I have read the contribution guidelines: https://github.com/AntennaPod/AntennaPod/blob/develop/CONTRIBUTING.md#submit-a-pull-request
• I have performed a self-review of my code
• I have run the automated code checks using ./gradlew checkstyle spotbugsPlayDebug spotbugsDebug :app:lintPlayDebug
• My code follows the style guidelines of the AntennaPod project: https://github.com/AntennaPod/AntennaPod/wiki/Code-style
• I have mentioned the corresponding issue and the relevant keyword (e.g., "Closes: #xy") in the description (see https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue)
• If it is a core feature, I have added automated tests

[ByteHamster]

Hi, thanks for your PR. Does using PackageManager take measurably more time than taking BuildConfig? I think if it doesn't, I would just keep it as is because that makes it easier to move the file to a different module later.

[aafanasev]

It's definitely faster than searching among all installed apps by package name as constants will be "inserted" at compilation time. However, it's not a bottleneck, if you prefer DevX over the minor performance that's ok.