This PR intended to fix #8686.
By adding following additional layout options to modern template.

• _disableNavbar
• _disableBreadcrumb
• _disableToc
• _disableAffix

Test
It's manually tested on my local environment.
And confirms that the following checks have been passed.

• When setting _disable* option. The corresponding elements is not be rendered in HTML.
• No JavaScript Error occurred when features are disabled.

Background
It seems some users are requesting above options. (#8686, #9116, #9296)
It can partially resolved by using _layout: landing option. (This option disable both toc and affix)
But there are feature requests that hide individual elements separately.