Many times, in order to create a `ven_pretty::Doc` containing a text
node, the pattern `alloc.text(format!(...))` would be used. This code
then creates a fresh string that is then used in the `Doc`. However,
many times only a small string is necessary and so the allocation could
be optimized. The `ven_pretty` crate supports this through a `SmallString`
type. Allocating a fresh string with `format!` also moves control away
from the `DocAllocator` which isn't ideal, since it could also handle
the string allocations. So, instead of creating a fresh string, one can
simply call `alloc.as_string(format_args!(...))` and delegate the
allocation to the `DocAllocator` without any loss in expressivity. So,
in order to encorage this pattern, this commit also introduces the
`text!` macro.
In order to find all instances of the code pattern, the following
tree-sitter query was used:
```scm
(call_expression
function: (field_expression
field: (field_identifier) @field.name
(#eq? @field.name "text"))
arguments: (arguments
(macro_invocation
macro: (identifier) @macro.name
(#eq? @macro.name "format")))) @reference.call
```
With a code like
```
thenDo = \x, callback ->
callback x
f = \{} ->
code = 10u16
bf = \{} ->
thenDo code \_ -> bf {}
bf {}
```
The lambda `\_ -> bf {}` must capture `bf`. Previously, this would not
happen correctly, because we assumed that mutually recursive functions
(including singleton recursive functions, like `bf` here) cannot capture
themselves.
Of course, that premise does not hold in general. Instead, we should have
mutually recursive functions capture the closure (haha, get it) of
values captured by all functions constituting the mutual recursion.
Then, any nested closures can capture outer recursive closures' values
appropriately.
