Provide a way to manually choose the text resource language

[cpetrov]

Feature description

Currently, the language to be picked when creating https://docs.tabris.com/latest/api/TextResources.html#class-textresources is determined from device.language and there is no way to give this language manually. Some apps' language configuration might be independent from the device language configuration.

Proposed solution

Provide an API to manually set the language manually when creating the text resource.