Page transitions animations

[andybar2]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

Feature

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

ng-web-app does not have animations on page transitions and does not handle errors from the backend endpoints.

• What is the new behavior (if this is a feature change)?

Page transitions animations added, and also a loading template while waiting for the data from the backend. Also en error template was included to handle backend endpoints errors.

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)

No

• Other information:

[andybar2]

@mitogh @adamf321 Could you review this PR when you have some time please?

[andybar2]

Ready @mitogh , thanks!