Glossary Entry import doesn't validate part_of_speech

[dd32]

It seems like the Glossary Import doesn't validate the value of the part_of_speech field, which can be problematic for two reasons:

• It doesn't display the "custom" value on the glossary page
• It causes PHP Notices in gp-templates/glossary-entry-row.php

For example, see the month entry on https://translate.wordpress.org/locale/fa/default/glossary/

I see two options here

• Reject entries which don't match a known value
• Display the value as-is

It looks like the mismatched values on WordPress.org can be translated, typos, and combinations (ie. adj, subst). Abbreviation was common enough that I've created #1199 for that.

[dd32]

Example notice:

PHP Notice: Undefined index: abbreviation   wp-content/plugins/glotpress/gp-templates/glossary-entry-row.php:4

[ocean90]

Yeah, we should reject any unknown value.