feat(alerting): Implement alert reminders (#1138)

* feat(alerting): add reminder-interval feature which allows setting an interval to run alert consecutively

* feat(test): add tests for reminder-interval feature

* feat(docs): modify documentation for reminder-interval feature

* chore: change "due" to "TRIGGERED" for easier log look through

* chore: update "reminder-interval" to "repeat-interval"

* chore: update reminder-interval to repeat-interval

* chore: adapt repeat interval feature after merge

* chore: adapt repeat interval feature after merge

* RepeatInterval => MinimumRepeatInterval

* fix merge issues

(cherry picked from commit 9b2161556bddf01d385f97dafac2515857190ae5)

* rename and move MiniumRepeatInterval

* move MiniumRepeatInterval (again)

---------

Co-authored-by: Bugra Kocabay <kocabay.bugra@gmail.com>
Co-authored-by: Bugra Kocabay <kocabaybugra@gmail.com>
Co-authored-by: Konstantin Nosov <nosovk@gmail.com>
Co-authored-by: Viktor Ziegler <Viktor.Ziegler@ti8m.ch>
Co-authored-by: TwiN <twin@linux.com>

alerting/alert/alert.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/TwiN/logr"
 	"gopkg.in/yaml.v3"
@@ -35,6 +36,9 @@ type Alert struct {
 	// SuccessThreshold defines how many successful executions must happen in a row before an ongoing incident is marked as resolved
 	SuccessThreshold int `yaml:"success-threshold"`
 
+	// MinimumReminderInterval is the interval between reminders
+	MinimumReminderInterval time.Duration `yaml:"minimum-reminder-interval,omitempty"`
+
 	// Description of the alert. Will be included in the alert sent.
 	//
 	// This is a pointer, because it is populated by YAML and we need to know whether it was explicitly set to a value