[performance] convert enum strings to ints (#3558)

* convert statuses.visibility and notifications.notification_type columns from type string -> int for performance / space savings

* fix test trying to compare string to int

* fix instance count query using string literal instead of gtsmodel const type

* ensure a default value is always set

* also migrate the account settings and sin bin status tables

* initialize maps outside loops and place into singular enum mapping creation func

* use int16 for enum types

* update sinbinstatus creation to be from a snapshot at initial creation

* add snapshot of poll type at creation time

1 files changed, 43 insertions, 12 deletions

diff --git a/internal/gtsmodel/status.go b/internal/gtsmodel/status.go
index 91c0ada61..f8bd068ab 100644
--- a/internal/gtsmodel/status.go
+++ b/internal/gtsmodel/status.go
@@ -263,27 +263,58 @@ type StatusToEmoji struct {
 	Emoji    *Emoji  `bun:"rel:belongs-to"`
 }
 
-// Visibility represents the visibility granularity of a status.
-type Visibility string
+// Visibility represents the
+// visibility granularity of a status.
+type Visibility enumType
 
 const (
 	// VisibilityNone means nobody can see this.
 	// It's only used for web status visibility.
-	VisibilityNone Visibility = "none"
-	// VisibilityPublic means this status will be visible to everyone on all timelines.
-	VisibilityPublic Visibility = "public"
-	// VisibilityUnlocked means this status will be visible to everyone, but will only show on home timeline to followers, and in lists.
-	VisibilityUnlocked Visibility = "unlocked"
+	VisibilityNone Visibility = 1
+
+	// VisibilityPublic means this status will
+	// be visible to everyone on all timelines.
+	VisibilityPublic Visibility = 2
+
+	// VisibilityUnlocked means this status will be visible to everyone,
+	// but will only show on home timeline to followers, and in lists.
+	VisibilityUnlocked Visibility = 3
+
 	// VisibilityFollowersOnly means this status is viewable to followers only.
-	VisibilityFollowersOnly Visibility = "followers_only"
-	// VisibilityMutualsOnly means this status is visible to mutual followers only.
-	VisibilityMutualsOnly Visibility = "mutuals_only"
-	// VisibilityDirect means this status is visible only to mentioned recipients.
-	VisibilityDirect Visibility = "direct"
+	VisibilityFollowersOnly Visibility = 4
+
+	// VisibilityMutualsOnly means this status
+	// is visible to mutual followers only.
+	VisibilityMutualsOnly Visibility = 5
+
+	// VisibilityDirect means this status is
+	// visible only to mentioned recipients.
+	VisibilityDirect Visibility = 6
+
 	// VisibilityDefault is used when no other setting can be found.
 	VisibilityDefault Visibility = VisibilityUnlocked
 )
 
+// String returns a stringified, frontend API compatible form of Visibility.
+func (v Visibility) String() string {
+	switch v {
+	case VisibilityNone:
+		return "none"
+	case VisibilityPublic:
+		return "public"
+	case VisibilityUnlocked:
+		return "unlocked"
+	case VisibilityFollowersOnly:
+		return "followers_only"
+	case VisibilityMutualsOnly:
+		return "mutuals_only"
+	case VisibilityDirect:
+		return "direct"
+	default:
+		panic("invalid visibility")
+	}
+}
+
 // Content models the simple string content
 // of a status along with its ContentMap,
 // which contains content entries keyed by