refactor(samples): changes with igniteui-theming

[simeonoff]

No description provided.

[didimmova]

• In shadows/card-sample-shadow.scss file the elevations function is being used and it doesn’t exist anymore in the theming package. Are we going to create a function like this there so we can keep using it?

• No surface color in palettes in app/theming/styles files

[simeonoff]

@didimmova All version references here need to be updated from 14.2.x. to 15.0.x.

[didimmova]

Fix the custom elevations color sample in shadows/card-sample-shadow.scss file

[simeonoff]

Fix the custom elevations color sample in shadows/card-sample-shadow.scss file

Done.