bug: keyboards.php should filter keyboard list according to device type

[mcdurdin]

We need to filter the keyboard list by phone, tablet, and desktop device. The cloud 4.0 API supports a device parameter https://help.keyman.com/developer/cloud/4.0/

For example, https://keymanweb.com/#am,Keyboard_gff_mesobe_fidelat supports mobile and tablet, but not desktop platforms.

Reported by @dyacob at https://community.software.sil.org/t/question-on-keyman-web-the-kmd-web-target/6972/9

[MakaraSok]

This seems to be related to https://community.software.sil.org/t/re-mesobe-on-ipad-running-ipados-16-1-1/7014.

[mcdurdin]

This seems to be related to https://community.software.sil.org/t/re-mesobe-on-ipad-running-ipados-16-1-1/7014.

I think that is a separate issue.