Admin collection Group default expanded/collapsed setting and reordered

[mustardpete]

Existing situation:
When adding collection to groups, in order to group them on the left nav, the groups are always expanded by default. This causes the left nav to get quite messy when you have a number of collections

Feature request:
Add config option to allow groups to be expanded/collapsed as a default state

Easy quick option:
Single config for defaulting all groups globally

Ideal more complete option:
Define the groups in a separate config object, this means the setting can be defined for each group and the groups can be ordered too as at the moment groups just pick up from the order they are added in admin but collections and globals cant be mix ordered

groups: [
	{
		name: 'group1',
		title: 'My Group 1',
		expanded: false,
	},
	{
		name: 'group2',
		title: 'My group2',
		expanded: true,
	}
	...
]

Then on the collection refer to the group name:

admin: {
    group: 'group1',
 },

If no groups object is set or is set to false, then fall back to working as it is now, using the string to group so not a breaking change