zjsunit: Move template module logic into load().
zjsunit: Move template module logic into load().

Unlike our normal mocks, we want mock_template
to call the actual code as well as the stub.

This preps us for the next commit.

eeshangarg/zulip,rht/zulip,rht/zulip,punchagan/zulip,kou/zulip,zulip/zulip,punchagan/zulip,andersk/zulip,andersk/zulip,hackerkid/zulip,punchagan/zulip,hackerkid/zulip,rht/zulip,zulip/zulip,kou/zulip,eeshangarg/zulip,eeshangarg/zulip,kou/zulip,punchagan/zulip,hackerkid/zulip,andersk/zulip,kou/zulip,rht/zulip,rht/zulip,andersk/zulip,hackerkid/zulip,punchagan/zulip,zulip/zulip,punchagan/zulip,rht/zulip,zulip/zulip,hackerkid/zulip,kou/zulip,andersk/zulip,punchagan/zulip,zulip/zulip,eeshangarg/zulip,hackerkid/zulip,zulip/zulip,rht/zulip,andersk/zulip,andersk/zulip,zulip/zulip,eeshangarg/zulip,hackerkid/zulip,kou/zulip,eeshangarg/zulip,kou/zulip,eeshangarg/zulip