chore(Angular Version): [On behalf of Planally Sdn Bhd]: Angular 18 migration

[msibhuiyan]

Please check if the PR fulfills these requirements

• The commit message follows our guidelines: https://github.com/moribvndvs/ng2-idle/blob/master/CONTRIBUTING.md#pr
• 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)
[X] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[X] Other... Please describe: Angular 18 migration

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

What is the new behavior?

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

[ ] Yes
[X] No

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

Other information:

[coveralls]

coverage: 100.0%. remained the same
when pulling bfb00ca on planally:ng-18
into fc7d369 on moribvndvs:master.

[moribvndvs]

So @ng-idle/core and keepalive both declare

"@angular/common": ">=17.3.10",
"@angular/core": ">=17.3.10"

as dependencies. Is this version sufficiently breaking that we need to bump these versions as well? I'm thinking maybe we don't since the packages don't export or otherwise rely on 18 specific things, with the exception of tests (which are irrelevant to consumers of these packages).

[coveralls]

coverage: 100.0%. remained the same
when pulling 250e0c3 on planally:ng-18
into fc7d369 on moribvndvs:master.

[msibhuiyan]

@moribvndvs If not major, I believe we could publish a minor version, As the bundle itself goes with the latest version of angular in the docs.
In the future, newer version of Angular migration should go smoothly.