settings: Rework MainActivity switching method

- Now it provides better UX by switching seamlessly without any
  blinking animation or loading dialog

Signed-off-by: Aayush Gupta <theimpulson@e.email>
1 job for backlog_2900-all-upstream in 5 minutes and 33 seconds (queued for 1 second)
Status Job ID Name Coverage
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passed #166192
build

00:05:33