Assign <blank> instead of, e.g., 0 to mean unused

[willf]

Pull Request Description

It's confusing to assign 0 to an argument to mean unused. So we'll set values to <blank> for unused arguments.
It's no longer possible to use "auto" to mean unused; "auto" can only mean "use OS-HPXML default".

Dehumidifier
Before

After

Related Pull Requests

OS-HPXML: NREL/OpenStudio-HPXML#1867.
Supersedes https://github.com/Test-Cloned-Org/resstock/pull/1312.

Related Issues

Closes NREL#1289.
Closes NREL#1293.

Checklist

Required:

• Technical reference documentation has been updated
• Add to the changelog_dev.rst file
• No unexpected regression test changes on CI (comparison artifacts have been checked)

Optional (not all items may apply):

• Tests (and test files) have been updated
• Supporting resource files have been updated (related to resstock-estimation)
  • data dictionary
  • source report
  • options saturation
  • options_lookup
• openstudio tasks.rb update_measures has been run

_{Source: NREL on 2024-10-25.}