Respect encoder maximum size constraint

Encoders cannot encode at any resolution.

Use video capabilities to constrain a given size by the limits of the
selected encoder.

These video capabilities describe the range of supported widths and
heights, as well as the supported heights for a given width (and
vice-versa). Use this information to compute the maximum portrait size
and the maximum landscape size.

PR #6766 <https://github.com/Genymobile/scrcpy/pull/6766>