Update slidepicker to meet minimum contrast for UI components

[gcamacho079]

Description

Updates slidepicker component to meet 3:1 contrast ratio for UI components (resolves DEV-685), and modifies size to meet draft SC 2.5.8 Target Size (Minimum)

Also removes low opacity set on settings button to meet minimum contrast ratio

Widget manager context:

Field layout context:

[linear[bot]]

DEV-685 Available widget columns do not meet minimum contrast

Page Area:

Dashboard - widget settings HUD

Issue Description:

The total number of columns is indicated by rectangles using a light hairline color. This hairline color is too light and makes it difficult for users with low vision to understand how many columns there are in total

Action:

Darken the border color of all available columns to meet 3:1 minimum contrast ratio. This will require that the width indicator uses something other than the darker outline to indicate the current selection

Screenshot/Code Snippet:

Screenshot showing colspan picker component with light indicator of total number of columns:

Screen Shot 2022-06-02 at 12.32.40 PM.png

Resolves CMS-230