Made CompassButton more customizable

[michalgwo]

As discussed in #250, I made Compass Button more customizable:

• allowed setting the size of the button
• allowed setting drawable of the needle

In addition, 2 changes that seemed reasonable:

• allowed setting content description of DisappearingCompassButton
• set the default content description of CompassButton to string resource, instead of hardcoded string

[westnordost]

Does this actually place the chosen icon in the center when a very large size is specified (or the icon is very small)?

[michalgwo]

Yes. The sizes on the screenshots are 30.dp and 300.dp. The icon is vector drawable with 24 dp height and 24 dp width, I don't think the size of the drawable matters as it's in the centre no matter how big the button is. What I noticed now, the icon may go out of bounds when the button is big enough (as you can see in the last screenshot), and barely noticeable, when the button is small, so it may be a good idea to have contentPadding customizable as well.

[michalgwo]

Now it looks better. I also made the shape of the button customizable, as it was the last thing that wasn't customizable.

[michalgwo]

Actually, it may be a good idea to make the default contentPadding depend on the size, instead of hardcoding 8.dp, any thoughts on this?

contentPadding: PaddingValues = PaddingValues(size / 6)

[sargunv]

Thanks for the PR! Looks reasonable to me, will review properly in a bit.

it may be a good idea to make the default contentPadding depend on the size, instead of hardcoding 8.dp, any thoughts on this?

That sounds good to me, though I don't have a strong preference either way.