[Windows] App - Always onTop

[bachig26]

Describe your suggested feature

i have few suggestions for this feature (which is similar to the other apps like a video player or notepad++ where it can be left always on top other running apps).

1. add an option to toggle to set the miru app being onTop.

2. since onTop feature important for the video player, which the current built-in player lacks, i'm not sure on the new branch for player. but if there's an PiP support [Windows] PiP support (if not possible, few other suggestions) #121 comes then it's an plus.
   @MiaoMint fyi, issue [Windows] PiP support (if not possible, few other suggestions) #121 is for the suggestion no.2, not no.1; just want to remind you in the current state on the new branch for the video player.

Acknowledgements

• I have searched the existing issues and this is a new ticket, NOT a duplicate or related to another open issue.