Automatic conversion to v2 for databases

At the moment all the database objects available in the test prefix (and probably the user's custom prefix) are not using "schema_version": 2. All the databases written in the previous version of the schema are read-only, therefore if a user wants to make a new version of a database, it is again read-only (not editable) which defeats the purpose of making a new version!

It is reasonable that when the user makes a new version of a database, instead of ending up with a read-only file, a new file for the database using "schema_version": 2 is created.

It will be good also that a message is shown to the user that there is a change in the schema_version, so they are aware of the change, and they won't be surprised when they look at the json file.

Steps to reproduce:

Open editor v2.
Go to File -> New -> databases -> New version
Click on Ok

the created database is read-only.

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