Fix TextField parameter ordering and sizing shenanigans

[rock3r]

This PR fixes two issues:

1. The two TextField composables differ in the orders of their trailingIcon and leadingIcon parameters #284
2. TextField layout logic:

• When there is a placeholder and leading and/or trailing icons, if the text field doesn't have a fixed width, the width jumps around
• In many cases, when the text field doesn't have a fixed height, focusing it or typing in it causes its height to change

Before	After

The fix for the second issue is to not consider the placeholder in the size calculation, which was a weird choice anyway. We likely inherited it from the Material EditText, that served as inspiration, but handles the placeholder very differently than we do.

Closes #284 and updates the sample code to use IconButton.