Automatically create documentation and deploy to GitHub Pages

[rdeago]

Scope and purpose of changes

Every good library needs documentation.

This PR adds automatic creation of web-based documentation and deploying to GitHub Pages upon every non-preview release from the main branch.

Types of changes

• Bug fix
• Enhancement (new and/or improved behavior)
• Other (please describe below)

Additions to Cake scripts and GitHub workflows.

Proposed changes / fixed issues

A new deploy-paged workflow is automatically dispatched by the Release Cake target immediately before publishing a release, provided that it is not a prerelease and the workflow runs on the main branch.

The new workflow:

• uses DocFx to extract API documentation from XML comments;
• uses DocFx to build the documentation site;
• uses GitHub actions to deploy the site to GitHub pages.

All static parts of the documentation site (home page, TOC, etc.) still have their default contents. A subsequent PR will provide more sensible contents; for now, testing the new workflow has a higher priority.

Contributor's checklist

• I have written tests for any provided enhancement
• I have written regression tests for any provided bug fix
• I have successfully run all tests on my machine
• I have added and/or updated related documentation (if applicable)
• I have updated the "Unreleased changes" section in CHANGELOG.md, according to the modifications I made

[rdeago]

Can't review a PR I opened myself. Disappointing, if you ask me.

[rdeago]

I'm going to test Squash and Merge with this PR. 🤞