Add `namespace:` and `updated_at:` query qualifier to `SearchAPI`

[wslulciuc]

Our searchAPI allows callers to query for jobs and datasets across namespaces. But, callers might need to narrow their search results by namespace. To enable callers to query for jobs and datasets within a namespace, let's add the namespace: qualifier:

• namespace:NAMESPACE: will match jobs or datasets within namespace NAMESPACE.

For example, the query (with filter=jobs):

my-best-job namespace:example

will match job(s) within namespace example with that name.

To filter by time of last updated, we're also adding the updated_at: qualifier:

• updated_at:<YYYY-MM-DD: will match jobs or datasets before YYYY-MM-DD.
• updated_at:>YYYY-MM-DD: will match jobs or datasets after YYYY-MM-DD.

Below, we add the updated_at: qualifier to our example job query from earlier:

my-best-job namespace:example updated_at:<2023-07-24

now, the query will match job(s) within namespace example with that name, that were also last updated before 2023-07-24 .

Note: These changes are in line with proposal 2180