fix(lints): prefer const declarations

[manjotsidhu]

Refer #149

Fix lint rules and clean analysis_options.yml -

• Remove the rules which are already enabled since they are true by default.
• Fixed prefer_const_declarations rule

[coveralls]

Pull Request Test Coverage Report for Build 1325154715

• 20 of 31 (64.52%) changed or added relevant lines in 16 files are covered.
• 9 unchanged lines in 8 files lost coverage.
• Overall coverage decreased (-0.5%) to 73.654%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/ui/views/authentication/forgot_password_view.dart	0	1	0.0%
lib/ui/views/authentication/login_view.dart	0	1	0.0%
lib/ui/views/groups/add_assignment_view.dart	2	3	66.67%
lib/ui/views/groups/update_assignment_view.dart	1	2	50.0%
lib/ui/views/ib/ib_landing_view.dart	0	1	0.0%
lib/ui/views/projects/edit_project_view.dart	0	1	0.0%
lib/ui/views/projects/project_details_view.dart	1	3	33.33%
lib/utils/router.dart	3	6	50.0%

Files with Coverage Reduction	New Missed Lines	%
lib/ui/views/about/about_privacy_policy_view.dart	1	96.12%
lib/ui/views/contributors/components/contributors_donate_card.dart	1	85.0%
lib/ui/views/contributors/components/contributors_support_card.dart	1	94.44%
lib/ui/views/home/components/feature_card.dart	1	93.33%
lib/ui/views/ib/ib_page_view.dart	1	59.57%
lib/ui/views/projects/featured_projects_view.dart	1	86.67%
lib/ui/views/teachers/components/teachers_card.dart	1	94.74%
lib/ui/views/projects/project_details_view.dart	2	36.3%

Totals
Change from base Build 1320117713:	-0.5%
Covered Lines:	3844
Relevant Lines:	5219

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💛 - Coveralls

[manjotsidhu]

@Neha62-lit you can review this

[Neha62-lit]

@Neha62-lit you can review this

Okay👍