Fix multiple tables scaling incorrectly

[LunarN0va]

This PR sets the table layout to fixed whenever a table has more than two columns. I'd love to hear your thoughts on this change.

Before:

After:

Tables with less than two columns don't have a fixed table layout:

But if this needs to change: this is what it would look like if the same table has a fixed table layout:

[jp7677]

I think this is a pretty good work around, but still somewhat fragile ;). I guess the decisions page (https://avisi-cloud.github.io/structurizr-site-generatr/main/internet-banking-system/decisions/) is still a but off with this PR.

I think a better and more consistent approach might be to handle a fixed percentage per column type. So e,g. give all columns with the name ID, Date and Status a width of 20%, columns for Systems, Technology and Name a width of 30%. Other columns might not need a set width.

[jp7677]

Superseded by #553