ID801705 fix required

[scblakely]

Bug ID 801705: When inserting a cookie or a cookie attribute, BIG-IP does not add a leading space, required by RFC

You can use the following to insert the leading space
HTTP::cookie attribute $a_cookie insert { SameSite}

In addition, setting the Secure flag with
HTTP::cookie secure
also has the same issue.

This should be replaced with
HTTP::cookie attribute $a_cookie insert { Secure}