[feature] add rate limit middleware (#741)

* feat: add rate limit middleware

* chore: update vendor dir

* chore: update readme with new dependency

* chore: add rate limit infos to swagger.md file

* refactor: add ipv6 mask limiter option

Add IPv6 CIDR /64 mask

* refactor: increase rate limit to 1000

Address https://github.com/superseriousbusiness/gotosocial/pull/741#discussion_r945584800

Co-authored-by: tobi <31960611+tsmethurst@users.noreply.github.com>

vendor/github.com/ulule/limiter/v3/limiter.go

@@ -0,0 +1,65 @@
+package limiter
+
+import (
+	"context"
+)
+
+// -----------------------------------------------------------------
+// Context
+// -----------------------------------------------------------------
+
+// Context is the limit context.
+type Context struct {
+	Limit     int64
+	Remaining int64
+	Reset     int64
+	Reached   bool
+}
+
+// -----------------------------------------------------------------
+// Limiter
+// -----------------------------------------------------------------
+
+// Limiter is the limiter instance.
+type Limiter struct {
+	Store   Store
+	Rate    Rate
+	Options Options
+}
+
+// New returns an instance of Limiter.
+func New(store Store, rate Rate, options ...Option) *Limiter {
+	opt := Options{
+		IPv4Mask:           DefaultIPv4Mask,
+		IPv6Mask:           DefaultIPv6Mask,
+		TrustForwardHeader: false,
+	}
+	for _, o := range options {
+		o(&opt)
+	}
+	return &Limiter{
+		Store:   store,
+		Rate:    rate,
+		Options: opt,
+	}
+}
+
+// Get returns the limit for given identifier.
+func (limiter *Limiter) Get(ctx context.Context, key string) (Context, error) {
+	return limiter.Store.Get(ctx, key, limiter.Rate)
+}
+
+// Peek returns the limit for given identifier, without modification on current values.
+func (limiter *Limiter) Peek(ctx context.Context, key string) (Context, error) {
+	return limiter.Store.Peek(ctx, key, limiter.Rate)
+}
+
+// Reset sets the limit for given identifier to zero.
+func (limiter *Limiter) Reset(ctx context.Context, key string) (Context, error) {
+	return limiter.Store.Reset(ctx, key, limiter.Rate)
+}
+
+// Increment increments the limit by given count & gives back the new limit for given identifier
+func (limiter *Limiter) Increment(ctx context.Context, key string, count int64) (Context, error) {
+	return limiter.Store.Increment(ctx, key, count, limiter.Rate)
+}