Elements with role "gridcell" must be contained in an element with the role "row"

**Describe the bug**

[Accessibility Insights](https://accessibilityinsights.io/) reports an issue with Masonic's accessibility markup.

Masonic [assigns a WAI-ARIA role](https://github.com/jaredLunde/masonic/blob/main/src/use-masonry.tsx#L79) of `grid` to the container, and a role of `gridcell` to each individual cell. However, [per W3C](https://www.w3.org/TR/2010/WD-wai-aria-20100916/roles#gridcell) there needs to be an element with role "row" around each visual row of cells:

> Authors MUST ensure elements with role gridcell are contained in, or owned by, an element with the role row.

**To Reproduce**
Run an Accessibility Insights FastPass scan on a web page using Masonic (the codesandbox demo works if you enable additional permissions for the extension to see the iframe). The error will be listed under "aria-required-parent".

**Expected behavior**
A Masonic grid should contain standards-compliant markup which passes an accessibility scan.

**Screenshots**
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**Desktop (please complete the following information):**

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**Smartphone (please complete the following information):**

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**Additional context**
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Start in src/use-masonry.tsx at the container and cell role assignments, then reproduce the aria-required-parent finding with Accessibility Insights FastPass. Determine how the visual rows are represented and update the markup so each gridcell is owned by a row; done means the Masonic grid passes the accessibility scan.

Written by the indexing model from the issue text.