String should be sanitized on hover

Nobody has claimed this yet.

### How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

### Which OS are you using?

Linux

### What is the issue affecting?

Hover

### Expected Behaviour

Consider the following code:

```lua
s = "one\ntwo\nthree"
```

When hovering over it, I'd expect to see the newline characters just as I wrote them in.

### Actual Behaviour

Instead, the newlines and tabs would get "expanded", breaking the way the hover looks.

### Reproduction steps

1. Create a string variable with newline (\n) or tab characters (\t)
2. hover over the variable

### Additional Notes

_No response_

### Log File

_No response_

Reproduce the issue by creating a Lua string containing newline or tab characters and hovering over the variable in the Visual Studio Code extension. Start at the language server's hover handling and trace how the string is formatted; done means the hover preserves the intended escaped characters without breaking its layout.

Written by the indexing model from the issue text.