Screen Sharing: Add enabled param to PrimaryButton Compose

Add enabled param to PrimaryButton with true as the default value.

screenshots:
enabled: http://screen/g2MXg4JKxCoSj6C
disabled: http://screen/C89FTQyajJYtAK3

Bug: 423707607
Test: none
Flag: com.android.systemui.large_screen_sharing
Change-Id: Ic8f8e493a95a1e051181a10bcbb91a530da7ccd6