An annotation for indicating that a function may error

Nobody has claimed this yet.

It would be pretty useful to have an indicator of whether the function may error (and thus needs to be handled with `pcall` or the like).
```lua
---@fallible
---@param bar string
---@return string bar
local function assert_is_foobar(bar)
if bar ~= "foobar" then
error("bar isn't equal to foobar")
end
return bar
end
```
I'm aware of #1881 but it doesn't fullfill the same purpose as `@fallible`, the main difference being the fact that `@noreturn` indicates that the function never returns while this indicates that the function could return an error

The LSP server could also potentially show the user a warning if they don't wrap a `@fallible` function in a `pcall` call

Start by reviewing how the language server currently handles the related @noreturn annotation and how it analyzes pcall usage. The issue does not name files or tests, and the intended warning behavior is described as optional, so the implementation scope and completion criteria need clarification before coding.

Written by the indexing model from the issue text.