add border to icon

[Jay-o-Way]

Description

Adds a border and background to the larger icon in the SidePanel.

Closes #1854

Motivation and Context

Clarity. This shows how any "overlay icons" are placed inside the available area. May help finding the right icon.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

[niels9001]

The tags are no longer showing up for me? Please revert those styling changes as they are not in scope for this issue and might introduce regressions with text scaling enabled.

[Zakariathr22]

Out of topic:
It's funny how simply wrapping a FontIcon inside a Border led us to all of this 😂

[niels9001]

@Jay-o-Way Please add the rounded corners (and optional padding to overcome to corner issue) as proposed by the design team, then we can get this in.

Thanks!

[Jay-o-Way]

@niels9001 Why don't you just finish it for me. Since we can't seem to agree on anything. Just do it your way.

[Jay-o-Way]

nit

[niels9001]

/azp run