fix(router-plugin): revert state back after "RouterCancel" is dispatched

[arturovt]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ngxs/store/blob/master/CONTRIBUTING.md#commit
• 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?

Issue Number: #542

What is the new behavior?

The state is reverted back

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[arturovt]

@markwhitfeld @splincode

This is bugfix for the very old #542 issue. Our router plugin doesn't revert state back, if the router emits NavigationCancel event in the current behavior. This is described in the issue and can be reproduced if any route has canDeactivate hook that returns false. The new behavior fixes it and reverts the state back as it has to be.

[markwhitfeld]

LGTM.
Great tests.