Follow-up to PR #64148 (bug 313737), which aligned C++/IPC method names with the Digital Credentials API spec ("chooser" instead of "picker") but deferred the ObjC API surface to keep that PR scoped. Scope of this bug — rename: - `WKDigitalCredentialsPicker` class → `WKDigitalCredentialsChooser` (and `.h`/`.mm` filenames) - `WKDigitalCredentialsPickerDelegate` protocol → `WKDigitalCredentialsChooserDelegate` - Protocol methods `digitalCredentialsPickerDid{Present,Dismiss}:` → `digitalCredentialsChooserDid{Present,Dismiss}:` - `_digitalCredentialsPicker` ivar in `WKContentViewInteraction.mm` and `WebViewImpl.mm` - `<WebKit/WKDigitalCredentialsPicker.h>` import in `WKWebView.mm` (and any other includers) Spec reference: Digital Credentials API §6.6 "Initiate the credential request" — https://w3c-fedid.github.io/digital-credentials/#initiate-the-credential-request — uses "digital credential chooser" throughout. Reviewer who flagged: @aprotyas (PR #64148 thread r3245130713). No behavioral changes.