chore: infer prettier parser from file extension

Issue
=====

The prettier parser was set to `typescript` in the `.prettierrc.json` file. Because prettier was
used for multiple files types, it caused errors when formatting files that were not TypeScript.

Here is an example:

```sh
README.md
[error] README.md: SyntaxError: Invalid character. (1:1)
[error] > 1 | # Neovim node.js client
[error]     | ^
[error]   2 |
[error]   3 | | CI (node >= 14, Linux/macOS/Windows) | Coverage | npm |
[error]   4 | |----------------------------|----------|-----|
```

This seems to cause the build to fail as of the most recent commit
7488014

Solution
========

Automatically infer the parser based on the file extension.

References:
- https://prettier.io/docs/en/configuration.html#setting-the-parserdocsenoptionshtmlparser-option

To make the build pass, run `npx prettier --write .` to format all files. I think it's best that
someone else does this, as it will change the formatting of many files (currently 43), and reviewing
them is very difficult.

.prettierrc.json

@@ -1,7 +1,6 @@
 {
   "tabWidth": 2,
   "trailingComma": "es5",
-  "parser": "typescript",
   "printWidth": 100,
   "singleQuote": true,
   "arrowParens": "avoid"