Allow cortextool rules load * (wildcard) as input.

[DandyDeveloper]

Since a proper tree structure can be defined because namespaces/groups exist for rules. It'd be nice if we could just wildcard the input to load all files in a directory via cortextool.

For exmaple;
Directory structure

tenant_a:
  rules:
     a.yml
     b.yml
     c.yml

tenant_b:
  rules:
     x.yml
     y.yml
     z.yml

Load in by calling cortextool rules load ./rules/tenant_a/*. This would load in rules a,b,c and vice-versa for alertmanager config and templates.

[DandyDeveloper]

Apparently this already exists and works... I swear this didn't like 3 weeks ago.

Sorry