Use the released CLI artifacts

[tdeebswihart]

What was changed

We use the pre-built CLI artifacts from the official releases rather than compiling them ourselves

Why?

Calculating the CLI's version based on the tag is a pain (see https://github.com/temporalio/docker-builds/pull/203) and I don't want to do that in our Makefile, so we're going to download the appropriate artifact from the official release instead

Note

This is gross but it works. I'm putting this up to stimulate discussion on how we should do it.

[tdeebswihart]

The version can be bumped automatically using sed:

$ sed -i '' 's/^CLI_VER.*/CLI_VER := v0.13.0/' Makefile

[robholland]

This should also fix https://github.com/temporalio/docker-builds/issues/107

[robholland]

Also makes progress on #43

[robholland]

Re-thinking this, I think we should build for temporaliotest and releases differently. Release builds should use released assets rather than building (action can prompt for the various release numbers). Test builds should just use whatever the submodules are at. We don't have the complex docker tags for test builds, so we don't have to calculate any tags.