Form.yml disable required on hidden elements

Hi All,

When working with dynamic fields in form.yml I noticed that if a hidden element has required: true the form will not be submittable unless the hidden element has a default value.

Here is an example:

  sub_type:
    label: Submission Environment
    widget: select
    help : Select desired submission environment.
    cacheable: false
    options:
      - [
          "Basic Modules", "mod_basic",
          data-hide-load-commands: true,
          data-hide-sif-file: true
        ]
      - [
          "Advanced Modules", "mod_adv",
          data-hide-sif-file: true
        ]
      - [
          "Container", "sif",
          data-hide-load-commands: true
        ]
  load_commands:
    label: Setup Commands (bash syntax)
    help: |
      Enter additional additional environment setup commands. These commands are run before starting MATLAB.

      - Load, or manipulate module environment using `module`
        - Extensions will only find programs provided by the module system if you load the required modules here!
      - Run arbitrary commands or source a bash script.
    cacheable: false
    widget: text_area
    placeholder: |
      module load <software-name>
      source "$HOME/project_a/setup-env.sh"
  sif_file:
    label: Container File
    help: |
      Select an Apptainer/Singularity Container (.sif/.simg) that includes [code-server](https://github.com/coder/code-server) 4.6.0 or newer.
    cacheable: false
    data-filepicker: true
    data-target-file-type: files
    data-target-file-pattern: '(.simg|.sif)$'
    readonly: true
    required: true

In this case the default for the form is to not use a container, but when the user elects to use a container we want to ensure that the a sif file is selected before the form can be submitted.