"Save" button shouldn't appear before one selects the source for a native question

[nemanjaglumac]

Describe the bug
Metabase currently displays the option to save a native question even before the source (db) for it is selected.

Logs

[backend]  "Input to adhoc-native-query-path does not match schema: \n\n\t   [(named (not (matches-some-precondition? nil)) database-or-id)]  \n\n",
[backend]  :value [nil],
[backend]  :error [(named (not (matches-some-precondition? nil)) database-or-id)]}

To Reproduce
Steps to reproduce the behavior:

1. Have more than one database (add another H2, for example)
2. New question > Native query
3. Without selecting a source database, note that the "Save" option is offered
4. Click on the "Save" - modal appears
5. Enter the name for your question and click "Save" button within the modal
6. Non-human-readable error appears inline

Expected behavior
The original "Save" button shouldn't even appear before it's actually possible to save the question

Screenshots

Information about your Metabase Installation:

You can get this information by going to Admin -> Troubleshooting.
local dev, master, 538a5e6, H2, Sample dataset

Severity
Although annoying, it's a cosmetic one and the backend handles this. P3.

[flamber]

Friends with #15946 (comment).