AddCatalogPriceForm: add tests

[0pdd]

The puzzle 1342-c6d2f2ba from #1342 has to be resolved:

mystamps/src/main/frontend/src/components/AddCatalogPriceForm.js

Line 5 in 7599f6b

// @todo #1342 AddCatalogPriceForm: add tests

The puzzle was created by Slava Semushin on 05-Jan-21.

[php-coder]

This issue depends on #1484 where Jest and all required test dependencies will be added.

[php-coder]

Isn't needed in light of HTMX migration (#1671).