Migrate BrowserTabViewModelTest and BrowserWebViewClientTest to Robolectric

[lmac012]

Task/Issue URL: https://app.asana.com/1/137249556945/task/1213242498673303

Description

Steps to test this PR

QA-optional

No UI changes

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Note

Low Risk
Test-only migration with lint-baseline churn; minimal production impact, but there’s some risk of behavior drift due to Robolectric vs device/runtime differences.

Overview
Migrates BrowserTabViewModelTest and BrowserWebViewClientTest from instrumentation (androidTest) to Robolectric/JVM (test) by switching to AndroidJUnit4 + @Config(sdk = [34]), replacing InstrumentationRegistry usage with RuntimeEnvironment, and dropping @UiThreadTest/@SdkSuppress gating.

Adds a reusable ValueCaptorObserver test helper, and adjusts test setup to better match Robolectric behavior (e.g., explicitly populating MimeTypeMap mappings and making TestWebView report progress=100). The lint baseline is updated to reflect moved test file paths and to remove prior denylisted-API entries tied to the old instrumentation tests.

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[lmac012]

• Migrate BrowserTabViewModelTest and BrowserWebViewClientTest to Robolectric #7729 👈 (View in Graphite)
• develop

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[GerardPaligot]

LGTM, but the build is failing due to lint errors from our new rule regarding impl module usage within the app module.