Create flexible config actions to place a block in the admin or default themes

Problem/Motivation

I want to place a block into a specific region as part of my recipe. In a module, I can do that using provided config (but only if I know the machine name of the default theme) or using an install hook. Recipes should provide a way to set configuration that will be applied to the default theme, without knowing the machine name of that theme when creating the recipe.

Proposed resolution

Create new placeBlockInDefaultTheme and placeBlockInAdminTheme config actions that will retrieve the appropriate theme name from the site configuration, and place the block in the appropriate theme.

The usage will look like this:

block.block.foo: # This block *should not* exist already!
  placeBlockInAdminTheme:
    # Pass a map of theme names to region names, because we don't know what the admin theme is, but want to have opinions about where it should go.
    region:
      olivero: content_above
      claro: header
      gin: sidebar
    default_region: content # If the current admin theme isn't one of the keys in `region`, use this region instead
    position: first # Can also be 'last'