Added the ability to get a list of available groups and a list of branches of each group.

In V7Preview4 it became possible to get a list of all groups, as well as a list of branches of any group, not just the current one.

Methods added:

• GetTerminalsGroups() - returns all existing groups
• GetRestaurantSectionsByTerminalsGroup(ITerminalsGroup terminalsGroup) - returns branches of the group specified in the arguments

In addition, the branch now has a link to the parent group: IRestaurantSection.TerminalsGroup

There will be no GetRestaurantSections method for getting branches of the current group in V7Preview4. You can use it instead

// Get all branches of the current group
var currentGroupSections = PluginContext.Operations.GetRestaurantSectionsByTerminalsGroup(PluginContext.Operations.GetHostTerminalsGroup());