Implement lists with the container block#52

There is no way to make <ul> or <ol> lists with GenerateBlocks that I know of, so I just use the core List block, which has always been pretty bad. (At least now, there are child List Item blocks - before it was just one big block.)

I think there is an obvious way to make a better list without significantly changing the Container in GB - just allow us to choose <ul> or <ol> in the Tag Name where we can currently choose div, section, etc.

Then any Container block marked as ul or ol can only have other containers under it, like the Grid block, and those containers must be tagged <li> and can contain whatever other blocks we want to put in them.

Maybe <dl> would be a good future addition too but ol and ul would definitely make things a lot better for me.

Done. GB 2.0 Block HTML Tags include:

ul, ol, dl