feat(api): Configurable response time badge thresholds (#309)

* recreated all changes for setting thresholds on Uptime Badges

* Suggestion accepted: Update core/ui/ui.go

Co-authored-by: TwiN <twin@linux.com>

* Suggestion accepted: Update core/ui/ui.go

Co-authored-by: TwiN <twin@linux.com>

* implemented final suggestions by Twin

* Update controller/handler/badge.go

* Update README.md

* test: added the suggestons to set the UiConfig at another line

Co-authored-by: TwiN <twin@linux.com>

config/config.go

@@ -16,6 +16,7 @@ import (
 	"github.com/TwiN/gatus/v4/core"
 	"github.com/TwiN/gatus/v4/security"
 	"github.com/TwiN/gatus/v4/storage"
+	"github.com/TwiN/gatus/v4/util"
 	"gopkg.in/yaml.v2"
 )
 
@@ -94,6 +95,16 @@ type Config struct {
 	lastFileModTime time.Time // last modification time
 }
 
+func (config *Config) GetEndpointByKey(key string) *core.Endpoint {
+	for i := 0; i < len(config.Endpoints); i++ {
+		ep := config.Endpoints[i]
+		if util.ConvertGroupAndEndpointNameToKey(ep.Group, ep.Name) == key {
+			return ep
+		}
+	}
+	return nil
+}
+
 // HasLoadedConfigurationFileBeenModified returns whether the file that the
 // configuration has been loaded from has been modified since it was last read
 func (config Config) HasLoadedConfigurationFileBeenModified() bool {