Add scale factor selector to Sticker tool

[MurzNN]

At now stickers are placed always at 100% scale, and can be resized after. But, for example, the "✔️" symbol is too large, and I need always to decrease its size manually. Will be good to have scale factor selector in Sticker tool panel, to tune-up default scale value before placing sticker.

[DamirPorobic]

Sounds more like the initial stickers are to large? How about scaling them down outside ksnip and importing it again? This feature request sound like an overkill for an issue that can be otherwise be better resolved.

[MurzNN]

Thanks for idea, I've done this for me! Bot most of users will use out-of-the-box stickers, and manual scaling-importing task is too hard for most of regular users. And some users like large stickers, other - small.

So setting default scale factor is more suitable solution for regular users, as I think.