fix(stark-demo): fix baseHref in angular.json file

[christophercr]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/NationalBankBelgium/stark/blob/master/CONTRIBUTING.md#-commit-message-guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

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

What is the current behavior?

The baseHref was removed from the angular.json file of the showcase due to PRs #471 and #477. However the showcase is broken since Angular requires a baseHref to be defined.

What is the new behavior?

Showcase correctly running since the baseHref is defined in the angular.json file.

Does this PR introduce a breaking change?

[ ] Yes
[X] No

[coveralls]

Coverage remained the same at 95.447% when pulling 2a36276 on christophercr:feature/showcase-basehref-fix into 6fc4fb3 on NationalBankBelgium:master.