Parse "Query.find always expects to find 1 element, but it found 2 instead." errors

Bug introduced in 3.6.2.

```html

A
A

```

```elm
ProgramTest.clickButton "A"
```

TODO:
- [ ] Add a failing test in `tests/ProgramTestTests/UserInput/ClickButtonTest.elm`
- [ ] grab the current error message from that and use it to add a test in `tests/ProgramTest/TestHtmlHacksTest.elm`
- [ ] implement parsing of the error message in `src/ProgramTest/TestHtmlParser.elm`
- [ ] make sure tests pass now
- [ ] update CHANGELOG.md
- [ ] PR should be made against or switched to the "develop" branch (not "main")

Reproduce the duplicate-button case with ProgramTest.clickButton "A" and add the failing test in tests/ProgramTestTests/UserInput/ClickButtonTest.elm. Use its error message to guide the test in tests/ProgramTest/TestHtmlHacksTest.elm, then inspect src/ProgramTest/TestHtmlParser.elm and CHANGELOG.md. Done means the error is parsed, all tests pass, and the changelog is updated; target the develop branch.

Written by the indexing model from the issue text.