Aligning translationIo integration with LinguiJS code standards

[timofei-iatsenko]

The packages/cli/src/services/translationIO.ts requires some work to be aligned with a code standarts of this project:

• Should compile with strict: true typescript option and dont have explicit/implicit any.
• Should be covered by unit test/integration tests with a coverage > 80%

Beside of the code quality i see a room for improvement, currently integration is operating with po file directly, and from what i'm seeing from the code it's not really requires to be in po format.

I'm thinking that from the consistency point of view the integration should not directly read / create catalog files, but it instead it should use lingui formatters.

This will bring benefits:

• files created by integration would use formatter options provided in lingui config
• potentially user can choose other formats, not only po
• no code duplication for serialization between lingui formatters and integration

FYI @MichaelHoste @didier-84