[Front-end]: Minor issues connected with localization

1.

Preconditions:
1. Billing is available on DataLab Web UI

Steps to reproduce:
1. Go to 'List of Resources' page

Actual result:
1. Billing on the 'List of Resources' page is not localized

Expected result:
1. Billing on the 'List of Resources' page is localized

2. Convert date period according to selected language for 'Billing report' page

3.  Convey language key to back-end for billing export (will do it in branch with back-end fix) - it will be done in task 2089.