Wrap LocationContext in useMemo

[dmarkow]

Fixes remix-run/remix#3672. LocationContext was using a new object every render, even if location and navigationType were the same. React's own docs recommend against this.

This update wraps the location context in a useMemo just like navigationContext.

I know "is this really hurting performance?" comes up often on this type of issue. For us the answer was definitely yes. We had a large data grid (5,000+ cells on the screen) where each cell needed the value of useLocation and clicking in a cell caused a fetcher to run. Even when we wrapped the cells in React.memo(), running the fetcher still caused every cell to re-render due to the context change. This did cause some noticeable lag on the page.

I've been running this patch in production since last summer with no issues.

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Latest commit: 771afa6

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[remix-cla-bot]

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[remix-cla-bot]

Thank you for signing the Contributor License Agreement. Let's get this merged! 🥳

[brophdawg11]

This is a subset of #9983 which I've been meaning to get to but have been busy with some other stuff. The only concern of mine in the other one is the need for the useBlocker change to fix breaking tests so I wanted to dig into that a bit deeper. I'll try to look into both this AM

[brophdawg11]

I combined this useMemo into #9983