fix: improve styles of the two column block, incorporating design tokens

Description

• improve display of the bulleted lesson list form in the editor (alignment and smaller delete buttons)
• make the styling match the designs - latest designs at https://www.figma.com/design/kHA0KOTrJyj1vq40RMSxKf/WGU-Design-System--WIP-?node-id=124-1067&t=HlQboO9Bh4lNoZnz-0 (private link)

Supporting information

Private-ref: https://tasks.opencraft.com/browse/BB-10774

Testing instructions

First, set up the wgu theme:

• clone and checkout https://github.com/open-craft/edx-simple-theme/pull/60
• in that repository, run npm run build && npm run serve
• switch to your devstack and add the tutor plugin described at https://github.com/open-craft/edx-simple-theme#using-a-local-theme
• restart your devstack

OR use the CI-deployed preview urls for the theme brandOverrides, instead of serving the theme locally, so the tutor plugin would look like:

from tutor import hooks
import json

paragon_theme_urls = {
    "core": {
        "urls": {
            "default": "https://cdn.jsdelivr.net/npm/@openedx/paragon@$paragonVersion/dist/core.min.css",
            "brandOverride": "https://theme-preview.sfo3.digitaloceanspaces.com/pr/60/core.css",
        }
    },
    "default": {
        "light": "light",
    },
    "variants": {
        "light": {
            "urls": {
                "default": "https://cdn.jsdelivr.net/npm/@openedx/paragon@$paragonVersion/dist/light.min.css",
                "brandOverride": "https://theme-preview.sfo3.digitaloceanspaces.com/pr/60/light.css"
            }
        }
    }
}

pargon_theme_config = f"""
MFE_CONFIG["PARAGON_THEME_URLS"] = {json.dumps(paragon_theme_urls)}
"""

hooks.Filters.ENV_PATCHES.add_item(
    (
        "mfe-lms-common-settings",
        pargon_theme_config
    )
)

Then you can test this:

• add some example two column blocks, ensuring you cover all the different column types
• verify they match the designs - latest designs at https://www.figma.com/design/kHA0KOTrJyj1vq40RMSxKf/WGU-Design-System--WIP-?node-id=124-1067&t=HlQboO9Bh4lNoZnz-0 (private link)
• in the code, verify that as many values as possible are controlled by theme variables, not hardcoded (NOTE: currently there are plenty hardcoded; these are due to limitations of the WIP nature of the theming, and they are commented inline)