Flyout > Create generic "action" button in header

[Blackbaud-SteveBrush]

Expected behavior

There should be a way to include a generic action button in the flyout's toolbar, to satisfy the Guidelines (see "Create list" button under the "Options" heading: https://developer.blackbaud.com/skyux/components/flyout#ux-guidelines).

Actual behavior

There is not a way to add an action button (the only button currently available is the permalink button, but it does not satisfy the need for a callback function.

Requirements

• Button should have configurable label and callback
• Config should look like (included in SkyFlyoutConfig):

primaryAction:? {
  label?: string;
  callback?: () => void
};

[Blackbaud-AlexKingman]

Resolved in #1766