error: allow to specify where to get error location

Currently, the error location (file, line) is always retrieved from
the current stack frame. The new argument `level` allows to change
this. It has the same semantics as the `level` argument of the built-in
Lua function `error`.

Closes #9792

@TarantoolBot document
Title: Document `level` argument of `box.error` and `box.error.new`

Now, when used with a table argument, `box.error` and `box.error.new`
also accept an optional second argument called `level`. It has the same
meaning as the `level` argument of the built-in Lua function `error`:
it specifies how to get the error location. With level 1 (the default),
the error location is where `box.error` / `box.error.new` was called.
Level 2 points the error to where the function that called `box.error` /
`box.error.new` was called; and so on. Passing level 0 avoids addition
of location information to the error.

Example of using `level` with `box.error`:

```lua
local json = require('json')

local function inner(level)
    box.error({message = 'test'}, level)    -- line:4
end

local function outer(level)
    inner(level)                            -- line:8
end

local ok, err
ok, err = pcall(outer)
print(json.encode(err.trace))               -- prints line:4
ok, err = pcall(outer, 1)
print(json.encode(err.trace))               -- prints line:4
ok, err = pcall(outer, 2)
print(json.encode(err.trace))               -- prints line:8
ok, err = pcall(outer, 0)
print(json.encode(err.trace))               -- prints empty table
```

Example of using `level` with `box.error.new`:

```lua
local json = require('json')

local function inner(level)
    local err = box.error.new({message = 'test'}, level)    -- line:4
    return err
end

local function outer(level)
    local err = inner(level)                                -- line:9
    return err
end

local err
err = outer()
print(json.encode(err.trace))               -- prints line:4
err = outer(1)
print(json.encode(err.trace))               -- prints line:4
err = outer(2)
print(json.encode(err.trace))               -- prints line:9
ok, err = pcall(outer, 0)
print(json.encode(err.trace))               -- prints empty table
```

It is also possible to specify `level` when using `box.error` to
re-raise an error created earlier with `box.error.new`, for example:

```lua
local json = require('json')

local err0 = box.error.new{message = 'test'}    -- line:3

local function raise(err, level)
    box.error(err, level)                       -- line:6
end

ok, err = pcall(raise, err0)
print(json.encode(err.trace))               -- prints line:3

ok, err = pcall(raise, err0, 1)
print(json.encode(err.trace))               -- prints line:6

ok, err = pcall(raise, err0, 0)
print(json.encode(err.trace))               -- prints empty table
```