[feature] Push notifications (#3587)

* Update push subscription API model to be Mastodon 4.0 compatible

* Add webpush-go dependency

# Conflicts:
#	go.sum

* Single-row table for storing instance's VAPID key pair

* Generate VAPID key pair during startup

* Add VAPID public key to instance info API

* Return VAPID public key when registering an app

* Store Web Push subscriptions in DB

* Add Web Push sender (similar to email sender)

* Add no-op push senders to most processor tests

* Test Web Push notifications from workers

* Delete Web Push subscriptions when account is deleted

* Implement push subscription API

* Linter fixes

* Update Swagger

* Fix enum to int migration

* Fix GetVAPIDKeyPair

* Create web push subscriptions table with indexes

* Log Web Push server error messages

* Send instance URL as Web Push JWT subject

* Accept any 2xx code as a success

* Fix malformed VAPID sub claim

* Use packed notification flags

* Remove unused date columns

* Add notification type for update notifications

Not used yet

* Make GetVAPIDKeyPair idempotent

and remove PutVAPIDKeyPair

* Post-rebase fixes

* go mod tidy

* Special-case 400 errors other than 408/429

Most client errors should remove the subscription.

* Improve titles, trim body to reasonable length

* Disallow cleartext HTTP for Web Push servers

* Fix lint

* Remove redundant index on unique column

Also removes redundant unique and notnull tags on ID column since these are implied by pk

* Make realsender.go more readable

* Use Tobi's style for wrapping errors

* Restore treating all 5xx codes as temporary problems

* Always load target account settings

* Stub `policy` and `standard`

* webpush.Sender: take type converter as ctor param

* Move webpush.MockSender and noopSender into testrig

vendor/github.com/rivo/uniseg/width.go

@@ -0,0 +1,61 @@
+package uniseg
+
+// EastAsianAmbiguousWidth specifies the monospace width for East Asian
+// characters classified as Ambiguous. The default is 1 but some rare fonts
+// render them with a width of 2.
+var EastAsianAmbiguousWidth = 1
+
+// runeWidth returns the monospace width for the given rune. The provided
+// grapheme property is a value mapped by the [graphemeCodePoints] table.
+//
+// Every rune has a width of 1, except for runes with the following properties
+// (evaluated in this order):
+//
+//   - Control, CR, LF, Extend, ZWJ: Width of 0
+//   - \u2e3a, TWO-EM DASH: Width of 3
+//   - \u2e3b, THREE-EM DASH: Width of 4
+//   - East-Asian width Fullwidth and Wide: Width of 2 (Ambiguous and Neutral
+//     have a width of 1)
+//   - Regional Indicator: Width of 2
+//   - Extended Pictographic: Width of 2, unless Emoji Presentation is "No".
+func runeWidth(r rune, graphemeProperty int) int {
+	switch graphemeProperty {
+	case prControl, prCR, prLF, prExtend, prZWJ:
+		return 0
+	case prRegionalIndicator:
+		return 2
+	case prExtendedPictographic:
+		if property(emojiPresentation, r) == prEmojiPresentation {
+			return 2
+		}
+		return 1
+	}
+
+	switch r {
+	case 0x2e3a:
+		return 3
+	case 0x2e3b:
+		return 4
+	}
+
+	switch propertyEastAsianWidth(r) {
+	case prW, prF:
+		return 2
+	case prA:
+		return EastAsianAmbiguousWidth
+	}
+
+	return 1
+}
+
+// StringWidth returns the monospace width for the given string, that is, the
+// number of same-size cells to be occupied by the string.
+func StringWidth(s string) (width int) {
+	state := -1
+	for len(s) > 0 {
+		var w int
+		_, s, w, state = FirstGraphemeClusterInString(s, state)
+		width += w
+	}
+	return
+}