Feature/tip navigation: New optional navigation options for the Showcase() widget

[mdrideout]

New feature to allow the developer to optionally enable the following features for each Showcase() widget:

• Navigation icons (forward / back)
• Counter / Pager to show where in the tutorial the user is
• End icon that allows the user to end the tutorial early

Features are off by default. Parameters are optional to avoid breaking old instances.

Example Photo

Showcase(
    key: _showcaseSettings,
    showTipCountIndex: true,
    showForwardBackNav: true,
    showEndIcon: true,
    description: ref.read(getMachineNavigationTipsProvider).getTipContent('settings_top'),
    child: Text(AppLocalizations.of(context)!.screenTitlesSettings, style: kTextStyleHeading2),
)

A developer could extend the Showcase() widget to pass their own default values.

[ujas-m-simformsolutions]

Hey @mdrideout, thank you for your contribution. Can you please resolve conflicts so that we can review your PR.