style: new converter grid layout

[M00NJ]

Some changes to the converter grid:

• I used 3 instead of 2 items in a row, since they're still big enough to tap, but now there's no scrolling required anymore to reach the items at the bottom.
• I used a different background color, since per guidelines there should only be one primary container per screen and because it was just to colorful imo.
• I kept the primary color for the icons though, which make them stand out more now.
• I renamed digital store to just storage to make the three items in a row layout possible. It also looks cleaner now, since it was the only string with two words. Also the old string name might cause problems with translation, like we've seen in ClockYou. I don't think there will be any confusion, since the icon makes it clear that it means digital storage.

Before	After (dark)	After (light)

[M00NJ]

I you prefer this style as well I can change the color mapping in the character input tab to match it.

[SuhasDissa]

Yea this style looks good

[M00NJ]

Can I merge these two PRs? We're good to go with the release then.