Deprecate `set_vx_params()` function

[mkavulich]

Description

As was briefly mentioned in #36, ush/set_vx_params.py is a vestige of the old bash system and is no longer needed. All info contained in there can be read from the config dictionary at runtime.

Solution

Deprecate set_vx_params(), move any info still needed to the config.

Requirements

Deprecate set_vx_params() to simplify the logic in runscripts, and increase runtime configurability.

Dependencies

This requires all runtime scripts be python-based, so #33 must be merged first.