WB-1638.1: Fix clickable behavior on IconButton (#2131)

## Summary:

First part in a series of fixes to Popover.

I recently removed `ClickableBehavior` from `IconButton` because some APIs have
improved in the last years making it easier to implement the same behavior
without the need of `ClickableBehavior`.

Turns out that I missed a few things, and this PR fixes them:

- Adds keyboard handlers to `IconButton` so that the click event can be
triggered the same way with `Enter` and `Space` keys. By not doing this, it was causing that the Popover was being immediately re-opened if the user pressed `Enter` on the close button.

- Prevents the button from displaying the pressed state after the user has
pressed the button with a mobile device (sticky active state).

Issue: WB-1638

## Test plan:

### 1. Normalized `Enter` and `Space` behavior:

In desktop, verify that the button can be pressed with `Enter` and `Space` keys
and that in both cases the button triggers the `onClick` callback only on key up.

Verify that a Popover is not immediately re-opened if the user presses `Enter` on the close button.

BEFORE

https://github.com/Khan/wonder-blocks/assets/843075/5585996a-dcab-4c5d-b89f-a7e203ca5df7

AFTER

https://github.com/Khan/wonder-blocks/assets/843075/0e7d165f-954d-4c24-beac-688df11f05d6

### 2. Prevent sticky active state on mobile devices:

In mobile, verify that the button doesn't display the pressed state after the
user has pressed the button.

BEFORE

https://github.com/Khan/wonder-blocks/assets/843075/d381f1a9-3401-4e9e-9070-e7f2c1af1bec

AFTER


https://github.com/Khan/wonder-blocks/assets/843075/ab5e682e-7483-403c-8c74-cacbf490c09f

Author: jandrade

Reviewers: jeresig

Required Reviewers:

Approved By: jeresig

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Pull Request URL: #2131

.changeset/rich-bottles-hope.md

@@ -0,0 +1,6 @@
+---
+"@khanacademy/wonder-blocks-icon-button": patch
+---
+
+Fixes keyboard behavior on IconButton:
+- Allows triggering onClick when Enter is pressed. - Fixes the active state from not being sticky on mobile devices.