feat: Prefer exact matches in getNodePath.

[sxn]

We've run into an issue where some of our pages were incorrectly matched during sitemap generation. After unsuccessfully trying to solve the issue on our side through various means, we decided to try and see if fixing it on the plugin's side would be accepted.

Description

This PR updates getNodePath to prefer exact matches instead of partial ones. As it currently stands, node is matched to the first entry in allSitePage.edges that matches const slugRegex = new RegExp(${node.path.replace(//$/, ``)}$, gi`)`

Given the following:

const node = { path: '/test/', … };
const allSitePage = { 
  edges: [
    { node: { url: '/some/test/', … }, … },
    { node: { url: '/test/', … }, … },
  ],
  …
};

getNodePath as it currently stands will (incorrectly) match node to allSitePage.edges[0] instead of the more appropriate allSitePage.edges[1].

This PR tries to fix this issue by doing both a partial and an exact match. If an exact match is found, then getNodePath immediately returns. If a partial match is found, it continues executing until either an exact match is found or the list is exhausted, at which point it will return the last partial match it finds.