panels: firmware-security: simplify the technical descriptions and panel

To reduce the amount of technical information to ordinary users, the panel and technical descriptions are simplified and reduced. The major revision is shown as follows:

1. The result of the check items view is removed and the detailed information can be found by copying them to the clipboard and pasting them to any place the users want.
2. The security status is only shown in the security dialog. All the bottoms are removed.
3. The loading spinner is added when the panel is launched.
4. A "status unavailable" page is added for the system which fwupd is unable to determine the security level.

Closes #2122 (closed)

Signed-off-by: Kate Hsuan hpa@redhat.com

• The loading spinner
• The security status dialog
• Showing the toast after clicking the button
• The page for "status unavailable"