[Bug][a11y]: SideNav: State of active SideNavItem lacks 3 to 1 contrast ratio.

### Code of conduct

- [X] I agree to follow this project's code of conduct.

### Impacted component(s)

SideNav, SideNavItem

### Expected behavior

The selected SideNavItem color MUST have at least a 3 to 1 luminosity contrast ratio with either the inner or outer adjacent background.

### Actual behavior

The selected SideNavItem color does not have at least a 3 to 1 luminosity contrast ratio with either the inner or outer adjacent background.

Color and contrast ratio details:
Selected state color: #EEEEEE
Adjacent background color: #FAFAFA
The contrast ratio is: 1.1:1

This is a failure of WCAG Success Criteria: [1.4.11 Non-text Contrast (Level AA) – WCAG 2.1](https://www.w3.org/TR/WCAG21/#non-text-contrast)
WCAG Understanding document: https://www.w3.org/WAI/WCAG21/Understanding/non-text-contrast

### Screenshots

### What browsers are you seeing the problem in?

_No response_

### How can we reproduce this issue?

1. Go to '...'
2. Click on '....'
3. Scroll to '....'
4. Check console
5. See error

### Sample code that illustrates the problem

_No response_

### Logs taken while reproducing problem

_No response_

Start by inspecting the SideNav and SideNavItem implementations and their selected-state styling. Compare the #EEEEEE selected color with the #FAFAFA adjacent background using WCAG 1.4.11 guidance; the work is done when the selected state reaches at least a 3:1 contrast ratio with an adjacent background.

Written by the indexing model from the issue text.