Make sure calls to `map.getProjection()` allows for conformal projection comparisons

Nobody has claimed this yet.

From @SnailBones in https://github.com/mapbox/mapbox-gl-js/pull/11460

>In the case w[here](https://mapbox.slack.com/archives/C0S9M8WUS/p1644354374673329?thread_ts=1644347492.436719&cid=C0S9M8WUS) we fallback to a stylesheet projection, the projection will be returned in the same format it appears in the stylesheet. i.e. center and parallels can be absent.
>
>This allows us to avoid storing another projection value (map._runtimeProjection or map._implicitProjection).
>
>The potential downside I see in this is that it could impose a challenge for users when attempting to check if two projections are the same. And as Ansis mentions here this could be a breaking change.
>
>One other option to avoid that would be adding a transform.standardizeProjection(projectionSpec) function and standardize the projection here before returning.

Refer https://github.com/mapbox/mapbox-gl-js/pull/11460#discussion_r802076835

Start with calls to map.getProjection() and the projection behavior discussed in pull request #11460. Review the linked pull-request discussion to determine how stylesheet projections with absent center and parallels should compare, and whether standardization belongs in transform.standardizeProjection(projectionSpec). Done means projection comparisons are unambiguous without introducing an additional stored projection value.

Written by the indexing model from the issue text.