feat(store) add overload for projector to inform about incorrect usage

[david-shortman]

PR Checklist

Please check if your PR fulfills the following requirements:

• 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?

[ ] 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?

Starts process on #3097

What is the new behavior?

A message on an overload for projector when it is used incorrectly:

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[ngrxbot]

Preview docs changes for 5662d21 at https://previews.ngrx.io/pr3223-5662d219/

[david-shortman]

@timdeschryver The docs-app test is failing, seemingly for a reason unrelated to the PR.

[timdeschryver]

@david-shortman 👍 you can leave it as is - we'll take a look at it.
For now, let's try a rerun.

[brandonroberts]

Needs a rebase

[david-shortman]

@brandonroberts The opt-in for strict projectors can take place in two ways:

export const selector = createSelector(
        selectUrl,
        url => url,
        { strict: true } // specify a `strict` flag, which means the developer can allow the Slices and Result to be inferred
      );

or

export const selector = createSelector<[string], string>( // directly supply generic arguments for Slices and Result
        selectUrl,
        url => url
      );

[david-shortman]

this type is not exported from the index so that developers do not create a dependency on this type (presuming it can one day be removed, and all memoized selectors have strict projectors).

instead, if a dev needs to declare the type of a variable, they can use the form MemoizedSelector<State, Result, (slices...Slices) => Result>

[david-shortman]

{ strict: true } is purely type information which is used by MemoizedSelector to determine which projector function is used.

[david-shortman]

Apparently this is known as an opaque type.

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[david-shortman]

closing and reopening with updates once #3354 is merged