As a user, I can configure the maximum number of issues to search in the Xray issue selector dialog

Whenever importing tests to an existing testset, there is currently a limitation of adding more than 100 tests.
Adding more than 100 tests is a normal situation, for example when creating a regression testset, so it should be supported.

A new option in the configuration should allow to change the maximum number of issues the Xray issue search dialog can retrieve.