Nope, everything does not have a cast time. Most of the skills are instant cast. You can check on the skill definition at the top (ps4).
e.g. Templar jabs/sweep , solar flare, radiant has cast time
or the soul strike ulti from soul magic skill line
You cannot animation cancel channeling (cast time) skills and you are vulnerable to attacks during channeling. It has a clear long animation and your damage is not instant, but during the whole attack animation. That is the difference, anyway, I am not going to debate on that.
Your answer is:
Just go with the tool tip. The skills with channeling time in the tool tip are the skills soul shine set buffs.
Hope this helps.