MM-23935 extend session expiry on user activity (#14275)

* MM-23935  extend session expiry on user activity

- if user types anything before a session expires the session will be extended to now + session length

- ensures new session expiries are not written to DB too frequently

- new session store func for updating session ExpiresAt

- session length defaults for mobile and web/ldap changed from 180 days to 30 days

web/context.go

@@ -182,6 +182,14 @@ func (c *Context) MfaRequired() {
 	}
 }
 
+// ExtendSessionExpiryIfNeeded will update Session.ExpiresAt based on session lengths in config.
+// Session cookies will be resent to the client with updated max age.
+func (c *Context) ExtendSessionExpiryIfNeeded(w http.ResponseWriter, r *http.Request) {
+	if ok := c.App.ExtendSessionExpiryIfNeeded(c.App.Session()); ok {
+		c.App.AttachSessionCookies(w, r)
+	}
+}
+
 func (c *Context) RemoveSessionCookie(w http.ResponseWriter, r *http.Request) {
 	subpath, _ := utils.GetSubpathFromConfig(c.App.Config())