Add realm specific implementation for List.add and List.insert

[nielsenko]

No description provided.

[coveralls]

Pull Request Test Coverage Report for Build 3023652286

• -1 of 7 (85.71%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+5.7%) to 92.891%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/src/list.dart	6	7	85.71%

Totals
Change from base Build 3013691132:	5.7%
Covered Lines:	392
Relevant Lines:	422

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 3036265550

• 7 of 7 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-1.2%) to 86.001%

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Totals
Change from base Build 3013691132:	-1.2%
Covered Lines:	1671
Relevant Lines:	1943

---

💛 - Coveralls

[blagoev]

I think we should add a test for the removeRange path of length setter

[nielsenko]

I think we should add a test for the removeRange path of length setter

I have added the requested test

[desistefanova]

Suggested change

	@override
	/// Setting the `length` is a required method on [List], but makes less sense
	/// for [RealmList]s. You can only decrease the length, increasing it throws an [RealmException].