MatDatepicker - WCAG 1.4.11 Issue

### Is this a regression?

- [ ] Yes, this behavior used to work in the previous version

### The previous version in which this bug was not present was

Present in all versions

### Description

The color of the _**secondary date**_ focus state indicator does not meet WCAG 1.4.11 requirements. It's currently at 1.6:1 and it needs to be 3:1 minimum.

https://www.w3.org/WAI/WCAG21/Understanding/non-text-contrast.html

Success Criterion [1.4.11 Non-text Contrast](https://www.w3.org/TR/WCAG21/#non-text-contrast) (Level AA): The visual [presentation](https://www.w3.org/WAI/WCAG21/Understanding/non-text-contrast.html#dfn-presentation) of the following have a [contrast ratio](https://www.w3.org/WAI/WCAG21/Understanding/non-text-contrast.html#dfn-contrast-ratio) of at least 3:1 against adjacent color(s):

**User Interface Components**
Visual information required to identify [user interface components](https://www.w3.org/WAI/WCAG21/Understanding/non-text-contrast.html#dfn-user-interface-component) and [states](https://www.w3.org/WAI/WCAG21/Understanding/non-text-contrast.html#dfn-state), except for inactive components or where the appearance of the component is determined by the user agent and not modified by the author;

**_Graphical Objects_**
Parts of graphics required to understand the content, except when a particular presentation of graphics is [essential](https://www.w3.org/WAI/WCAG21/Understanding/non-text-contrast.html#dfn-essential) to the information being conveyed

[WCAG 1.4.11 - Mat Datepicker.docx](https://github.com/angular/components/files/9243949/WCAG.1.4.11.-.Mat.Datepicker.docx)

### Reproduction

Steps to reproduce:
1. Open the datepicker component
2. Tab into the individual dates
3. Select to pick an active date
4. Go back into datepicker and use arrow keys to move to between non-selected dates

### Expected Behavior

Color contrast should be 3:1 or higher

### Actual Behavior

Color contrast for the secondary date when in focus is 1.6:1

### Environment

- Angular: 12.2
- CDK/Material: 12.2
- Browser(s): Edge and Chrome
- Microsoft Edge - Version 103.0.1264.71 (Official build) (64-bit)
- Chrome - Version 103.0.5060.134 (Official Build) (64-bit)
- Operating System (e.g. Windows, macOS, Ubuntu): Windows 10 Enterprise

Commencez par reproduire le problème de datepicker en suivant les étapes au clavier indiquées, puis examinez le document WCAG 1.4.11 joint et les captures d’écran. Identifiez le style de l’état de focus secondaire de la date, puis vérifiez que son contraste avec les couleurs adjacentes atteint au moins 3:1 et que le comportement de datepicker reste correct.

Rédigé par le modèle d'indexation à partir du texte de l'issue.