mypy: Fully use ViewFuncT in decorators.py; remove WrappedViewFuncT.
mypy: Fully use ViewFuncT in decorators.py; remove WrappedViewFuncT.

Many declarations were previously annotated with
Callable[..., HttpResponse]; this is equivalent to ViewFuncT, so here we
switch to it.

To enable this migration, the WrappedViewFuncT alias is removed; this is
equivalent to the simple & legible Callable[[ViewFuncT], ViewFuncT], so
for relatively no space change, a clearer return type is possible.

punchagan/zulip,punchagan/zulip,zulip/zulip,timabbott/zulip,showell/zulip,synicalsyntax/zulip,zulip/zulip,tommyip/zulip,rishig/zulip,jackrzhang/zulip,dhcrzf/zulip,shubhamdhama/zulip,eeshangarg/zulip,dhcrzf/zulip,tommyip/zulip,dhcrzf/zulip,punchagan/zulip,eeshangarg/zulip,timabbott/zulip,shubhamdhama/zulip,hackerkid/zulip,brainwane/zulip,andersk/zulip,brainwane/zulip,punchagan/zulip,dhcrzf/zulip,kou/zulip,zulip/zulip,dhcrzf/zulip,hackerkid/zulip,rht/zulip,synicalsyntax/zulip,shubhamdhama/zulip,kou/zulip,kou/zulip,rht/zulip,eeshangarg/zulip,jackrzhang/zulip,rishig/zulip,tommyip/zulip,rishig/zulip,zulip/zulip,synicalsyntax/zulip,kou/zulip,synicalsyntax/zulip,brainwane/zulip,eeshangarg/zulip,jackrzhang/zulip,jackrzhang/zulip,rht/zulip,brainwane/zulip,hackerkid/zulip,punchagan/zulip,rishig/zulip,shubhamdhama/zulip,rht/zulip,hackerkid/zulip,synicalsyntax/zulip,hackerkid/zulip,andersk/zulip,showell/zulip,brainwane/zulip,andersk/zulip,rishig/zulip,brainwane/zulip,eeshangarg/zulip,showell/zulip,zulip/zulip,kou/zulip,rishig/zulip,andersk/zulip,tommyip/zulip,eeshangarg/zulip,tommyip/zulip,shubhamdhama/zulip,brainwane/zulip,shubhamdhama/zulip,jackrzhang/zulip,rishig/zulip,punchagan/zulip,punchagan/zulip,showell/zulip,hackerkid/zulip,showell/zulip,dhcrzf/zulip,timabbott/zulip,tommyip/zulip,timabbott/zulip,zulip/zulip,hackerkid/zulip,showell/zulip,kou/zulip,andersk/zulip,showell/zulip,shubhamdhama/zulip,timabbott/zulip,rht/zulip,jackrzhang/zulip,jackrzhang/zulip,rht/zulip,timabbott/zulip,timabbott/zulip,andersk/zulip,synicalsyntax/zulip,tommyip/zulip,synicalsyntax/zulip,kou/zulip,eeshangarg/zulip,andersk/zulip,zulip/zulip,rht/zulip,dhcrzf/zulip