Stripe rows tables via theme and other theme nested overrides

[dy]

Oftentimes we have a situation in project when we need to redefine nested elements styles via theme. (We tend to use theme instead of styling each component individually because we need extensive skinning support).

The cases:

• defining different ripple color for IconButton hover/active states.
• defining TableBody > TableRow stripe pattern (not just generic TableRow, eg. TableHead > TableRow should not be affected)
• reduce icon size for ListItemIcon in MenuItem

For now that seems to be impossible to do.

We'd expect something like

    MuiTableBody: {
      MuiTableRow: {
        root: {
          "&:nth-of-type(odd)": {
            backgroundColor: "rgba(251,251,251,1)"
          }
        }
      },
    },

I hoped there could be a simple nesting introduced to overrides, since class selectors are meaningless due to CSS mangling in production.

Related: #5286

@oliviertassinari @eps1lon @mbrookes

[oliviertassinari]

@dy Could it be a duplicate with #15002?

[dy]

Yes, I think that's it. Ok, just listed additional cases then.