[FEATURE] PPL Sort with `num`, `str`, or `ip`

[currantw]

Is your feature request related to a problem?

PPL has unimplemented sorting syntax:

• sort auto(field_name)
• sort num(field_name)
• sort str(field_name)
• sort ip(field_name)

While this syntax is currently valid, it has no effect on the resulting sort order - sorting is always performed according to the field's data type.

Based on the discussion below, it seems like this would be a useful feature that would both easier to use, and consistent with sorting in Splunk.

What solution would you like?

• Implement sorting with num, str, and ip keywords.
• Remove auto keyword from sorting syntax (consensus seems to be that this isn't particularly useful).

What alternatives have you considered?

Variety of alternatives, including deprecating this syntax completely, were discussed below.

Do you have any additional context?

Related to opensearch-project/sql#3180 (same issue for SQL).

[currantw]

Updated for consistency with corresponding SQL issue: opensearch-project/sql#3180