chan_sip: Attempt ast_do_pickup in handle_invite_replaces

When a call pickup is performed using and invite with replaces header
the ast_do_pickup method is attempted and a PICKUP stasis message is sent.

ASTERISK-28081 #close
Reported-by: Luit van Drongelen

Change-Id: Ieb1442027a3ce6ae55faca47bc095e53972f947a