feat: add ffetch.js for indexing

[twhite313]

Please always provide the GitHub issue(s) your PR is for, as well as test URLs where your change can be observed (before and after):

Fix #131

Test URLs:

• Original: https://www.esri.com/en-us/about/about-esri/overview
• Before: https://main--esri--aemsites.hlx.live/
• After: https://fetch--esri--aemsites.hlx.live/

[aem-code-sync[bot]]

Hello, I'm the AEM Code Sync Bot and I will run some actions to deploy your branch and validate page speed. In case there are problems, just click a checkbox below to rerun the respective action.

• [ ] Re-run PSI checks
• [ ] Re-sync branch

Commits

* [364f3d9](https://github.com/aemsites/esri/commit/364f3d9ad63ab67e31b5a96e6c70b73108e4ffdb) :white_check_mark: (latest) * [cbb5cdf](https://github.com/aemsites/esri/commit/cbb5cdfe4d87a8d5e1ea9840894472b2c99f2668) :white_check_mark: * [2be4933](https://github.com/aemsites/esri/commit/2be49330220d4854253a524c19fc7a5d46941bb9) :white_check_mark:

[aem-code-sync[bot]]

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