[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

internal/api/client.go

@@ -47,6 +47,7 @@ import (
 	"github.com/superseriousbusiness/gotosocial/internal/api/client/notifications"
 	"github.com/superseriousbusiness/gotosocial/internal/api/client/polls"
 	"github.com/superseriousbusiness/gotosocial/internal/api/client/preferences"
+	"github.com/superseriousbusiness/gotosocial/internal/api/client/push"
 	"github.com/superseriousbusiness/gotosocial/internal/api/client/reports"
 	"github.com/superseriousbusiness/gotosocial/internal/api/client/search"
 	"github.com/superseriousbusiness/gotosocial/internal/api/client/statuses"
@@ -91,6 +92,7 @@ type Client struct {
 	notifications       *notifications.Module       // api/v1/notifications
 	polls               *polls.Module               // api/v1/polls
 	preferences         *preferences.Module         // api/v1/preferences
+	push                *push.Module                // api/v1/push
 	reports             *reports.Module             // api/v1/reports
 	search              *search.Module              // api/v1/search, api/v2/search
 	statuses            *statuses.Module            // api/v1/statuses
@@ -143,6 +145,7 @@ func (c *Client) Route(r *router.Router, m ...gin.HandlerFunc) {
 	c.notifications.Route(h)
 	c.polls.Route(h)
 	c.preferences.Route(h)
+	c.push.Route(h)
 	c.reports.Route(h)
 	c.search.Route(h)
 	c.statuses.Route(h)
@@ -183,6 +186,7 @@ func NewClient(state *state.State, p *processing.Processor) *Client {
 		notifications:       notifications.New(p),
 		polls:               polls.New(p),
 		preferences:         preferences.New(p),
+		push:                push.New(p),
 		reports:             reports.New(p),
 		search:              search.New(p),
 		statuses:            statuses.New(p),