docs: provide example for global ErrorStateMatcher for standalone apps

[michael-small]

Relevant documentation page: https://material.angular.io/components/input/overview#changing-when-error-messages-are-shown
Edit: other page https://material.angular.io/components/select/overview#changing-when-error-messages-are-shown

ErrorStateMatcher is very useful, especially when added globally. This PR would add an example on how to use it globally in standalone applications.

[mmalerba]

Can you split these into 2 separate code blocks? When its shown as one, I worry people might think they need to copy the entire snippet

[michael-small]

Good idea. Can it be two adjacent blocks like this

// NgModule applications
@NgModule({
  providers: [
    {provide: ErrorStateMatcher, useClass: ShowOnDirtyErrorStateMatcher}
  ]
})

// Standalone applications
export const appConfig: ApplicationConfig = {
  providers: [
    {provide: ErrorStateMatcher, useClass: ShowOnDirtyErrorStateMatcher}
  ]
};

or should the comments be pulled out into something like normal text above the blocks

[michael-small]

@mmalerba sorry if it's gauche to @ you but I just remembered this PR.

Thoughts?

[crisbeto]

Looking through old docs PRs: this needs a rebase.

[michael-small]

Looks like #32840 covered this recently, very nice. Closing.

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