Prepare 1.0.0-rc.1 release

[felixarntz]

This issue is to track preparation of the upcoming 1.0.0-rc.1 release up until publishing, which is due April 4, 2022.

• Define scope and tentative release date based on the scope
• Create release/1.0.0-rc.1 branch closer to the release date
• Merge updates from (previously created) release/1.0.0-beta.4 branch into release/1.0.0-rc.1 branch (see Merge extra enhancements landed in beta.4 branch into new rc.1 branch #273)
• Prepare the release (Monday, April 4, 2022)

[felixarntz]

cc @mitogh @bethanylang