[BadgeUtils] Expose Espresso matchers to match attached drawable

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**Is your feature request related to a problem? Please describe.**
A clear and concise description of what the problem is.
Currently, when adding espresso tests, aiming to cover `BadgeUtils.attachBadgeDrawable` there is no way to write fluent assertions on the badge produced by `BadgeUtils`

**Describe the solution you'd like**
A clear and concise description of what you want to happen.
I'd expect to have class similar to i.e. ` androidx.test.espresso.contrib.RecyclerViewActions` which would expose convenient utilities to assert i.e.
`onView(fixtureView).check(matches(hasBadgeDrawable(contentDesritpion = "View updates")))`

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.
I tried to set `setContentDescriptionNumberless` or `setContentDescriptionQuantityStringsResource` but there is no way to assert them using Espresso :/
I tried to write custom matcher accessing `view#getOverlay` but ViewOverlay's api seems to be too restricted
I tried to use reflection to read `ViewOverlay`'s drawables but this obviously doesn't work on recent android versions

**Additional context**
Add any other context or screenshots about the feature request here.

We also happily accept [pull requests](https://github.com/material-components/material-components-android/pulls).

Start by locating BadgeUtils.attachBadgeDrawable and the existing Espresso matcher utilities or tests in the repository. Determine how an assertion can observe the attached badge drawable and define completion as a matcher that verifies the badge content description through Espresso.

Written by the indexing model from the issue text.