Hide upload button from default toolbar when attachments is set to false

[AlexB52]

Fixes #307

Based on the discussion on issue #307, this also works and could be enough?
Happy to provide a change for either approach

:where(lexxy-editor) {
  &[attachments="false"] button[name="upload"] {
    display: none;
  }
}

[kcamcam]

Could it be worth testing that the button is still present when false or blank?

test "enable attachments" do
  visit edit_post_path(posts(:empty), attachments_disabled: [false, nil].sample)

  assert_no_selector "lexxy-toolbar button[name=upload]"
end

[AlexB52]

Sounds good. I've updated the tests.

Note: The form on the page edit_post_path(posts(:empty), attachments_disabled: true) also needed a change for the test to work. To some extent, we're more testing the query parameter than the actual attachments attribute with these new tests.

[AlexB52]

I've rebased onto basecamp/lexxy/main to update the js builds to the latest version.

[AlexB52]

This is a bit annoying as this change now diverges from the other query parameter disabling option logic on L15: params[:toolbar_disabled] ? "false" : nil