referrals: add "use expiry" option

adds an option when enabling referrals to use the duration of the source
invited (i.e., months, days, hours) for the referral invite. If enabled,
the user won't be able to make a new referral link after it expires. For
referrals enabled for new users via a profile, the clock starts ticking
as soon as the account is created.

ts/modules/accounts.ts

@@ -783,6 +783,7 @@ export class accountsList {
     private _userSelect = document.getElementById("modify-user-users") as HTMLSelectElement;
     private _referralsProfileSelect = document.getElementById("enable-referrals-user-profiles") as HTMLSelectElement;
     private _referralsInviteSelect = document.getElementById("enable-referrals-user-invites") as HTMLSelectElement;
+    private _referralsExpiry = document.getElementById("enable-referrals-user-expiry") as HTMLInputElement;
     private _searchBox = document.getElementById("accounts-search") as HTMLInputElement;
     private _search: Search;
 
@@ -1578,7 +1579,7 @@ export class accountsList {
                 send["from"] = "invite";
                 send["id"] = this._referralsInviteSelect.value;
             }
-            _post("/users/referral/" + send["from"] + "/" + (send["id"] ? send["id"] : send["profile"]), send, (req: XMLHttpRequest) => {
+            _post("/users/referral/" + send["from"] + "/" + (send["id"] ? send["id"] : send["profile"]) + "/" + (this._referralsExpiry.checked ? "with-expiry" : "none"), send, (req: XMLHttpRequest) => {
                 if (req.readyState == 4) {
                     toggleLoader(button);
                     if (req.status == 400) {
@@ -1593,6 +1594,7 @@ export class accountsList {
         };
         this._enableReferralsProfile.checked = true;
         this._enableReferralsInvite.checked = false;
+        this._referralsExpiry.checked = false;
         window.modals.enableReferralsUser.show();
     }