lib: TLS session ticket caching reworked

Described in detail in internal doc TLS-SESSIONS.md

Main points:
- use a new `ssl_peer_key` for cache lookups by connection filters
- recognize differences between TLSv1.3 and other tickets
  * TLSv1.3 tickets are single-use, cache can hold several of them for a peer
  * TLSv1.2 are reused, keep only a single one per peer
- differentiate between ticket BLOB to store (that could be persisted) and object instances
- use put/take/return pattern for cache access
- remember TLS version, ALPN protocol, time received and lifetime of ticket
- auto-expire tickets after their lifetime

Closes #15774

lib/llist.h

@@ -75,6 +75,10 @@ size_t Curl_llist_count(struct Curl_llist *list);
 /* Curl_node_elem() returns the custom data from a Curl_llist_node */
 void *Curl_node_elem(struct Curl_llist_node *n);
 
+/* Remove the node from the list and return the custom data
+ * from a Curl_llist_node. Will NOT incoke a registered `dtor`. */
+void *Curl_node_take_elem(struct Curl_llist_node *);
+
 /* Curl_node_next() returns the next element in a list from a given
    Curl_llist_node */
 struct Curl_llist_node *Curl_node_next(struct Curl_llist_node *n);