in JS, `new TextDecoder("latin1").decode(...)` uses cp1252. In python,
latin1 is half-width utf-16. In our code, latin1 typically refers to
half-width utf-16 because JavaScriptCore uses that for most strings, but
sometimes it refers to cp1252. Rename the cp1252 functions to be called
cp1252
Also fixes an issue where Buffer.from with utf-16le would sometimes
output the wrong value:
```js
$> bun -p "Buffer.from('\x80', 'utf-16le')"
<Buffer ac 20>
$> node -p "Buffer.from('\x80', 'utf-16le')"
<Buffer 80 00>
$> bun-debug -p "Buffer.from('\x80', 'utf-16le')"
<Buffer 80 00>
```
c69ed120e9