Get rid of twitter embeds

[captainbrosset]

Some tips are just links to tweets, and there's a plugin in the build system that turns those into tweet embeds.

This is bad because it takes time to load, requires javascript, can't be previewed in the tip list pages, and depends on twitter being available at all.

Let's convert those into actual tips on the site.

[captainbrosset]

There are currently 6 tips that are just tweets:

• src\tips\en\console-table-group-assert.md
• src\tips\en\debug-js-hover-2.md
• src\tips\en\fix-color-contrast-issues.md
• src\tips\en\quickly-reference-things-from-console.md
• src\tips\en\screenshot-part-of-page-command-menu.md
• src\tips\en\use-designmode-to-spell-check.md

They can be found easily in the source code by searching for isTweet.

These tips only contain the URL to a tweet, and the build system replaces this URL with the right embedding code so that the real tweet appears at runtime for users visiting those pages.

The goal of this issue is to:

1. Replace these tips with actual text and images, coming from those tweets.
2. Keep a link to the original tweet at the end, to credit the person who shared the tip on tweeter.
3. Remove the support for isTweet from the build system: search for isTweet in the rest of the code and remove the corresponding lines of code, and remove the usage of eleventy-plugin-embed-twitter in the .eleventy.js config file.

[captainbrosset]

Fixed with 4fb8a80d98e9c699844e86975c78169be87449f8.