Be strict about layer names, migrate existing

[fm3]

In some places we added a restriction for layer names ([A-Za-z0-9_\\-\\.]* + does not start with dot).

This is to ensure easy handling of the names both in uris and file paths.

We should be strict about that in all places (validateDataSource, submitJob, frontend, sql constraints).

To do that we first need to migrate all existing layers.

Note that we also discussed adding $ and @ to the list of valid characters