Add Back toolbar button to QuizLTI webview

[rh12]

refs: MBL-18184
affects: Student, Teacher, Parent
release note: none

QuizLTI back button at the bottom toolbar is now visible when the webview is navigated forward (which means there is someting to go back to)

Test plan

• Verify back button appears when QuizLTI webview navigates to another screen and disappears when tapping back.
• Smoke test back navigation works from Module to Dashboard.

Screenshots TODO

Before	After

Checklist

• A11y checked
• Tested on phone
• Tested on tablet
• Tested in dark mode
• Tested in light mode

[inst-danger]

Parent Build QR Code:

[inst-danger]

Teacher Build QR Code:

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Student Build QR Code:

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	Warnings
⚠️	This pull request will not generate a release note.
⚠️	One or more files are below the minimum test coverage 50%

Affected Apps: Student, Teacher, Parent

MBL-18184

Coverage	New %	Master %	Delta
Canvas iOS	91.35%	91.35%	0%
Core/Core/Common/CommonModels/Store/FetchedCollection.swift	48.72%	48.72%	0%
Core/Core/Common/Extensions/Foundation/CGSizeExtensions.swift	0%	0%	0%
Core/Core/Features/Courses/SmartSearch/Model/CourseSmartSearchViewAttributes.swift	30.77%	30.77%	0%
Core/Core/Common/Extensions/SwiftUI/UIColor+Color.swift	0%	0%	0%
Core/Core/Features/Search/Model/SearchSupportButtonModel.swift	0%	0%	0%
Core/Core/Common/CommonModels/AppEnvironment/AppEnvironmentOverride.swift	32.76%	32.76%	0%

Generated by 🚫 dangerJS against 9d92081

[vargaat]

QA+1, thanks for the refactor!

[suhaibabsi-inst]

QA +1
Tested on iOS 18.2.1, Student App.