MM-30740 Add support for boolean feature flags. (#16311)

* Add support for boolean feature flags.

* Tests

* Use strconv.ParseBool to accept additional values as true.

* Update config/feature_flags.go

Co-authored-by: Christopher Poile <cpoile@gmail.com>

Co-authored-by: Christopher Poile <cpoile@gmail.com>
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

model/feature_flags.go

@@ -7,6 +7,9 @@ type FeatureFlags struct {
 	// Exists only for unit and manual testing.
 	// When set to a value, will be returned by the ping endpoint.
 	TestFeature string
+	// Exists only for testing bool functionality. Boolean feature flags interprate "on" or "true" as true and
+	// all other values as false.
+	TestBoolFeature bool
 
 	// Toggle on and off scheduled jobs for cloud user limit emails see MM-29999
 	CloudDelinquentEmailJobsEnabled bool
@@ -14,5 +17,6 @@ type FeatureFlags struct {
 
 func (f *FeatureFlags) SetDefaults() {
 	f.TestFeature = "off"
+	f.TestBoolFeature = false
 	f.CloudDelinquentEmailJobsEnabled = false
 }