feat: custom UI terms and conditions

[Samo8]

Fixes #489

Implemented Parameters

backgroundColor - Dialog background color
titleColor - Title text color
mainTextColor - Main terms text color
acceptButtonTextColor - Accept button text color
cancelButtonTextColor - Cancel button text color

Not Implemented

Typography (Cross-platform)

More complex problem that can be handled in different PR
Title font (Android: setTitleTypeface(), iOS: titleFont)
Main text font (Android: setMainTextTypeface(), iOS: mainTextFont)
Button font (Android: setButtonsTypeface(), iOS: buttonsFont)

Text Sizes (Android only)

Android only can be handled in different PR
setTitleTextSize() - Title text size
setMainTextTextSize() - Main text size
setButtonsTextSize() - Button text size

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I signed the CLA.
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation
• I added new tests to check the change I am making
• All existing and new tests are passing.

[jokerttu]

The Android version wasn’t building. I added a few suggestions that should resolve the Android build issues.

Native Navigation SDK for Android seems to have internal bug with uiParams as the background color always leaks outside of the panel where dropshadow should be.

There is example implementation of this feature to example pages, camera, navigation_without_map and turn_by_turn.
If possible it would be nice to have this on navigation and navigation_without_map example pages only to keep the example pages simple and as those are main navigation related example pages. What do you think?

Please add a new integration test in https://github.com/googlemaps/flutter-navigation-sdk/blob/main/example/integration_test/t02_session_test.dart
that verifies uiParams. Because the integration tests run on both platforms (Android emulator and iOS simulator), this should also help detect potential crashes in the native implementations.

iOS Test:

Android Test (after suggested fixes):

[Samo8]

@jokerttu thanks for suggestions, all should be applied now

[jokerttu]

LGTM, once the suggested small improvement is included.

The default font sizes in TermsAndConditionsUIParams.Builder do not match those used in the standard TOS dialog. This change aligns the defaults to match the standard dialog.

[jokerttu]

Hard code default text sizes on Android to match the default TOS dialog.

Suggested change

	.build()
	// TODO: Make text sizes configurable via TermsAndConditionsUIParamsDto.
	// Currently hardcoded to match the Navigation SDK default values.
	.setButtonsTextSize(14)
	.setMainTextTextSize(14)
	.setTitleTextSize(20)
	.build()

Default TOS without TermsAndConditionsUIParams.

With TermsAndConditionsUIParams before suggested changes:

With TermsAndConditionsUIParams after suggested changes: