Add cookieSecure and cookieSameSite config options

[edclements]

Summary

• Adds a cookieSecure config option (default false) that appends the secure attribute to cookies set by Ahoy, for sites served over HTTPS.
• Adds a cookieSameSite config option (default "lax", matching current behavior) so the samesite attribute can be changed to "strict" or "none" as needed.

Usage

ahoy.configure({
  cookieSecure: true,
  cookieSameSite: "strict"
});