feat(menu): Add selected property to menu items

[trimox]

Change as per material-components-web v0.30.0
reference: material-components/material-components-web#2084

Adds mdc-list-item--selected class to menu items when rememberSelection is set to true.

New Public methods

• Add setRememberSelection(rememberSelection: boolean)
• Add getSelectedIndex(): number
• Add setSelectedIndex(index): void
• Add setMaxHeight(height: number): void

Closes #618

[codecov]

Codecov Report

Merging #665 into master will increase coverage by 0.45%.
The diff coverage is 72.72%.

@@            Coverage Diff             @@
##           master     #665      +/-   ##
==========================================
+ Coverage   91.89%   92.35%   +0.45%     
==========================================
  Files         156      156              
  Lines        6011     6027      +16     
  Branches      966      966              
==========================================
+ Hits         5524     5566      +42     
+ Misses        487      461      -26

Impacted Files	Coverage Δ
src/lib/menu/menu-module.ts	100% <100%> (ø)	⬆️
src/lib/menu/menu.ts	91.36% <70%> (+10.97%)	⬆️
src/lib/snackbar/snackbar.component.ts	91.48% <0%> (+3.54%)	⬆️

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