NetworkPkg: Avoid memory allocation for each HTTP message exchange.

This patch updates the HTTP driver to use a shared buffer for URL parsing to
avoid memory allocation for each HTTP request.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Fu Siyuan <siyuan.fu@intel.com>
Reviewed-by: Ye Ting <ting.ye@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18449 6f19259b-4bc3-4df7-8a09-765794883524