Add 'dis' component

This commit adds a new 'dis' component to the distillery that serves a
list of all known instances for the moment.

core/requirements.go

@@ -0,0 +1,26 @@
+package core
+
+import (
+	"github.com/tkw1536/goprogram"
+	"github.com/tkw1536/goprogram/meta"
+)
+
+// Requirements are requirements for the WissKI Distillery
+type Requirements struct {
+	// Do we need an installed distillery?
+	NeedsDistillery bool
+}
+
+// AllowsFlag checks if the provided flag may be passed to fullfill this requirement
+// By default it is used only for help page generation, and may be inaccurate.
+func (r Requirements) AllowsFlag(flag meta.Flag) bool {
+	return r.NeedsDistillery
+}
+
+// Validate validates if this requirement is fullfilled for the provided global flags.
+// It should return either nil, or an error of type exit.Error.
+//
+// Validate does not take into account AllowsOption, see ValidateAllowedOptions.
+func (r Requirements) Validate(arguments goprogram.Arguments[Flags]) error {
+	return nil
+}