Add UI for specifiers that include both a specimen identifier and a scientific name

[gaurav]

Even when a specifier is a specimen, we usually also have information about the taxon or taxon concept that it had been identified to when the clade definition was created. It would be useful to record this information as well.

[gaurav]

While this is supported by the Phyx format, support for this feature has not yet been implemented in Klados.

[gaurav]

Depends on #232

[gaurav]

• Add a universal identifier (UUID) as a field Moved to Add UUIDs to specimen specifiers #320
• Other than that, actually implementing specimens with taxon names isn't a priority.

[gaurav]

Since implementing specimens with taxon name is no longer a priority (especially since specimens are rarely used in phyloreferences), I'm going to move this to enhancements not necessary for v1.0, and create a new issue just for adding UUIDs to specimens.