I looked for a quick release handlebar bag and couldn't find one. BUT, a regular backpack can be modified to do the trick, rolling up to mount and with an attached brace to hold off at the stem or head tube. I won't say that it's easy, but I'm sure that one could work out a variation of this. I've been using this most days for months and it works great. Rolling up means that it can be stuffed to various amounts, or used as a backpack if completely full. Or when off the bike.

I took those hooks off and inserted flat hooks into the bag's padded straps instead so that's an older photo. Putting it on I set the hooks on the handlebar, pull an elastic strap around the back of the stem and that's it. To remove it I simply pull straight up and it instantly transforms into a backpack!

The keys to this are: having some way to keep the bag rolled up, hooks secure over the top of the handlebar, a strap of some sort around the back side of the stem/head tube, and a built-in stand-off from the stem or head tube. If you have all of these, the bag is kept from sagging, onto the wheel for example on more aggressive road bike geometry.