Update max age of securecookie codecs when setting cookie store options

[awhitefox]

This PR fixes a bug where setting cookie store options using .Options(...) does not update the MaxAge of its codecs. This leads to gorilla's securecookie cryptography not respecting the store's MaxAge and using the default value of 86400 * 30. Because of this, securecookie would accept expired cookies if store's MaxAge is lower than the default value or reject fresh cookies if it's higher.

Here is how CookieStore setup is done in gorilla/sessions (source):

func NewCookieStore(keyPairs ...[]byte) *CookieStore {
	cs := &CookieStore{
		Codecs: securecookie.CodecsFromPairs(keyPairs...),
		Options: &Options{
			Path:     "/",
			MaxAge:   86400 * 30,
			SameSite: http.SameSiteNoneMode,
			Secure:   true,
		},
	}

	cs.MaxAge(cs.Options.MaxAge)
	return cs
}

A cs.MaxAge(cs.Options.MaxAge) call is made to set MaxAge for codecs (source):

func (s *CookieStore) MaxAge(age int) {
	s.Options.MaxAge = age

	// Set the maxAge for each securecookie instance.
	for _, codec := range s.Codecs {
		if sc, ok := codec.(*securecookie.SecureCookie); ok {
			sc.MaxAge(age)
		}
	}
}

This PR adds the same call to gin's cookie store .Options(...) receiver:

func (c *store) Options(options sessions.Options) {
	c.CookieStore.Options = options.ToGorillaOptions()
	c.CookieStore.MaxAge(options.MaxAge) // Set the maxAge for securecookie codecs
}