[ADF-5406] SCSS and HTML template path fixes

[DenysVuika]

Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What kind of change does this PR introduce? (check one with "x")

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation
• Other... Please describe:

What is the current behaviour? (You can also link to an open issue here)

What is the new behaviour?

Important: This is a prerequisite for Angular 11/12 upgrade, it reduces the amount of efforts needed for upgrade

• fix issues the templateUrl paths
• fix issues with the double scss bundling (mixins)
• reduce useless mixins where possible
• reduce $mat-small and $mat-xsmall (deprecated/removed in Angular 12)

Does this PR introduce a breaking change? (check one with "x")

• Yes
• No

If this PR contains a breaking change, please describe the impact and migration path for existing applications: ...

Other information:
https://alfresco.atlassian.net/browse/ADF-5406

[pmartinezga]

Is it ok having this empty file demo-shell/src/app/components/cloud/start-process-cloud-demo.component.scss?

[pmartinezga]

empty demo-shell/src/app/components/cloud/start-task-cloud-demo.component.scss?

[DenysVuika]

@pmartinezga empty css files is considered an anti-pattern from what I recall, and puts some pressure on the compile time

[dhrn]

/rebase