Fix formatting of Kotlin source and XMLs

[codekarma]

• Fixed formatting of Kotlin source file through ktfmt
• Fixed indentations in manifest xmls
• Fixed a readme of addManifestPlaceholderFromTask

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[ducrohet]

Thanks for this pull request (and sorry for having ignored it for a long time). At this time, we cannot accept contributions to the 7.x branch. Our mechanism for these branches is quite problematic. The source of truth is in our internal server, organized in a very different way than what is published on github.

The good news is that for 8.x and beyond we have a new process that will allow us to take contributions. You can already look at the studio-main branch and make contribution there. Note that the recipe are not usable as-is there, and we have a tool to help. I'm actually in the process of cleaning this up a bit and documenting it better. Please take a look again next week.

With this setup we'll be able to update all agp-* branches (for AGP 8.x+)