feat(store devtools): export INITIAL_OPTIONS for consuming via provid…

[ttestman4]

…er (#1470)

PR Checklist

Please check if your PR fulfills the following requirements:

• [ X] The commit message follows our guidelines: https://github.com/ngrx/platform/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?
This enhancement allow large scale projects to pass options using providers

[ ] Bugfix
[X] 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?

Current behaviour force to pass config option via forRoot to StoreDev tools. This make large scale project, where library initialization is abstracted out to library project, difficult to pass the options

Closes # 1470

What is the new behavior?

Configuration options can be passed using angular providers to StoreDevtools

Does this PR introduce a breaking change?

[ ] Yes
[X] No

Other information

[ngrxbot]

Preview docs changes for 396c221 at https://previews.ngrx.io/pr2405-396c221/