Make language mappings deterministic

[kbairak]

Consider this scenario: Someone has in their config file:

[main]
lang_map = it: it-IT

[RESOURCE_ID]
lang_map = it: it_IT

Before we created a local-to-remote map that looked like this:

{"it-IT": "it", "it_IT", "it"}

And then, to create the remote-to-local map, we reversed it. The problem was that, since both values are the same, the key that ended up being selected was random, so it could either be:

{"it": "it-IT"}

or

{"it": "it_IT"}

To fix the issue, we now create remote-to-local first, going over the global configuration first and the resource-level configuration second so that the resource-level will prevail and thus take preference, and then we create the local-to-remote by reversing. So,

First, we will consume the global configuration:

{"it": "it-IT"}

Then, as the resource-level configuration is consumed, it will replace the old key:

{"it": "it_IT"}

And then, the local-to-remote will end up being:

{"it_IT": "it"}

This is the deterministic and the intended behaviour, since resource-level configuration should take precedence.