Dashboard Migrations v16: Grid layout migration (#109603)

* Migration to be verified: v17 Convert minSpan to maxPerRow in panels

* Address review comments: use Go idiom for variable naming and sort.Ints for sorting

* Migration to be verified: 16 Grid layout migration

* Refactor v17 and v19 migrations to use shared helper functions

* Address reviews comments

---------

Co-authored-by: Haris Rozajac <58232930+harisrozajac@users.noreply.github.com>
Co-authored-by: Haris Rozajac <haris.rozajac12@gmail.com>

apps/dashboard/pkg/migration/schemaversion/migration_utils.go

@@ -0,0 +1,79 @@
+package schemaversion
+
+// migration_utils.go contains shared utility functions used across multiple schema version migrations.
+
+// GetStringValue safely extracts a string value from a map, returning empty string if not found or not a string
+func GetStringValue(m map[string]interface{}, key string) string {
+	if value, ok := m[key]; ok {
+		if s, ok := value.(string); ok {
+			return s
+		}
+	}
+	return ""
+}
+
+// GetBoolValue safely extracts a boolean value from a map, returning false if not found or not a boolean
+func GetBoolValue(m map[string]interface{}, key string) bool {
+	if value, ok := m[key]; ok {
+		if b, ok := value.(bool); ok {
+			return b
+		}
+	}
+	return false
+}
+
+// GetIntValue safely extracts an integer value from a map, returning defaultValue if not found or not convertible
+func GetIntValue(m map[string]interface{}, key string, defaultValue int) int {
+	if value, ok := m[key]; ok {
+		if i, ok := ConvertToInt(value); ok {
+			return i
+		}
+	}
+	return defaultValue
+}
+
+// GetFloatValue safely extracts a float value from a map, returning defaultValue if not found or not convertible
+func GetFloatValue(m map[string]interface{}, key string, defaultValue float64) float64 {
+	if value, ok := m[key]; ok {
+		if f, ok := ConvertToFloat(value); ok {
+			return f
+		}
+	}
+	return defaultValue
+}
+
+// ConvertToFloat converts various numeric types to float64
+func ConvertToFloat(value interface{}) (float64, bool) {
+	switch v := value.(type) {
+	case float64:
+		return v, true
+	case int:
+		return float64(v), true
+	case int64:
+		return float64(v), true
+	case float32:
+		return float64(v), true
+	case int32:
+		return float64(v), true
+	default:
+		return 0, false
+	}
+}
+
+// ConvertToInt converts various numeric types to int
+func ConvertToInt(value interface{}) (int, bool) {
+	switch v := value.(type) {
+	case int:
+		return v, true
+	case float64:
+		return int(v), true
+	case int64:
+		return int(v), true
+	case float32:
+		return int(v), true
+	case int32:
+		return int(v), true
+	default:
+		return 0, false
+	}
+}