[WIP] Fix ban by software version, some other under-hood changes

- Use updated version of upstream go-xmpp + fixes on client-side
- Introduce golangci-lint v2 + fixes
- Move especially noisy debugging stuff to separate config handles to be able to switch them off
- Add a bit debug to ban by software path

vendor/github.com/xmppo/go-xmpp/xmpp_subscription.go

@@ -0,0 +1,30 @@
+package xmpp
+
+import (
+	"fmt"
+)
+
+func (c *Client) ApproveSubscription(jid string) {
+	fmt.Fprintf(c.stanzaWriter, "<presence to='%s' type='subscribed'/>\n",
+		xmlEscape(jid))
+}
+
+func (c *Client) RevokeSubscription(jid string) {
+	fmt.Fprintf(c.stanzaWriter, "<presence to='%s' type='unsubscribed'/>\n",
+		xmlEscape(jid))
+}
+
+// Deprecated: Use RevertSubscription instead.
+func (c *Client) RetrieveSubscription(jid string) {
+	c.RevertSubscription(jid)
+}
+
+func (c *Client) RevertSubscription(jid string) {
+	fmt.Fprintf(c.conn, "<presence to='%s' type='unsubscribe'/>\n",
+		xmlEscape(jid))
+}
+
+func (c *Client) RequestSubscription(jid string) {
+	fmt.Fprintf(c.stanzaWriter, "<presence to='%s' type='subscribe'/>\n",
+		xmlEscape(jid))
+}