fix(core): codegen should generate unique route prop filenames

[slorber]

Motivation

Fix #10125

When using docs routeBasePath: '/' and a category with slug: '/', we end up with 2 prop module files named index.json in the plugin props dir, and one overrides the other leading to issues.

To solve this, we now always append a hash (previously there was an exception for path / returning index) that depends on both the route path but also the component name. It makes it much less likely to have a filename conflict.

Note: it's still technically possible to have a conflict. A more robust solution could be to hash the props object content, but it's slower. The current solution is good enough and fast.

Test Plan

Unit test

Plus local test on the bug repro works:

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[github-actions]

⚡️ Lighthouse report for the deploy preview of this PR

URL	Performance	Accessibility	Best Practices	SEO	PWA	Report
/	🟠 70	🟢 98	🟢 96	🟢 100	🟠 88	Report
/docs/installation	🟠 63	🟢 96	🟢 100	🟢 100	🟠 88	Report
/docs/category/getting-started	🟠 77	🟢 100	🟢 100	🟢 90	🟠 88	Report
/blog	🟠 67	🟢 100	🟢 100	🟢 90	🟠 88	Report
/blog/preparing-your-site-for-docusaurus-v3	🟠 59	🟢 96	🟢 100	🟢 100	🟠 88	Report
/blog/tags/release	🟠 70	🟢 100	🟢 100	🟠 80	🟠 88	Report
/blog/tags	🟠 76	🟢 100	🟢 100	🟢 90	🟠 88	Report

[github-actions]

Size Change: -33 B (0%)

Total Size: 1.71 MB

Filename	Size	Change
website/build/assets/js/main.********.js	853 kB	-33 B (0%)

ℹ️ View Unchanged

Filename	Size
website/.docusaurus/codeTranslations.json	2 B
website/.docusaurus/docusaurus.config.mjs	26.9 kB
website/.docusaurus/globalData.json	107 kB
website/.docusaurus/i18n.json	930 B
website/.docusaurus/registry.js	275 kB
website/.docusaurus/routes.js	179 kB
website/.docusaurus/routesChunkNames.json	119 kB
website/.docusaurus/site-metadata.json	2.17 kB
website/build/assets/css/styles.********.css	112 kB
website/build/index.html	38.1 kB

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