Fixes #2756 Libraries and many other modals share the Modal Component.

Connected the Modal container to redux to make it aware of the RTL state, and then made sure that all places that use the modal component import the container, not the component directly.

* Added localization for ‘Make a Block’
* ‘block name’ default text is in scratch-blocks

The changes in `error-step.jsx` were needed because the same id was defined in there and `unavailable_step.jsx`. The scripts to generate the json file for Transifex give an error if the same id is defined in two places. In error step it simply uses the id without redefining default value etc. The alternative would be to add a new messages.jsx file that has the definitions for shared text and include that in both places that use them.