fix: preserve empty property values in CLI

[mj006648]

Rationale for this change

The properties get table and properties get namespace commands used a truthy check for property lookups. As a result, an existing property with an empty string value was reported as missing.

This changes both lookups to check explicitly for None, preserving empty strings while keeping the existing error for missing properties.

Related to #3713.

Are these changes tested?

Yes. Added CLI regression tests for empty table and namespace property values.

• make lint
• uv run python -m pytest tests/cli/test_console.py

Are there any user-facing changes?

Yes. The table and namespace property commands now return an existing empty string value instead of raising NoSuchPropertyException.

[kevinjqliu]

LGTM, great catch!

[kevinjqliu]

slight nit: i think we can simplify this whole block like so

    if not property_name:
        output.describe_properties(namespace_properties)
        return

    property_value = namespace_properties.get(property_name)
    if property_value is None:
        raise NoSuchPropertyException(f"Could not find property {property_name} on namespace {identifier}")

    output.text(property_value)

but this can be a follow up PR 😄