With tree sequences from real data, some of the metadata columns are likely to take up quite a lot of space (e.g. most of the storage). It would be helpful to know this when looking at a tree sequence e.g. with tskit info.

At the moment, we just report "Has Metadata: No/Yes" for each table. Might it be more informative to give "Metadata: None/XXX bytes" instead? In the html output we could simply put some sort of null marker (e.g. ∅, or just left blank) versus the byte size, rather than ✅.

We could either report the size of the metadata column, or the size of the metadata + metadata_offset columns. I guess the first makes a little more sense.