[idea] Rename `module` into `teal_module` (and also `modules` into `teal_modules`)

A proposal: rename `module()` into `teal_module()` (and similarily `modules()` into `teal_modules()`).

Reasons:
- in line with argument `data` that accepts what `teal_data()` returns
- avoid confusion internally between `modules` argument value and `modules()` function

As a result we would be having something like this:
```
init(
data = teal_data() |> ...
modules = teal_modules(
teal_module(...)
...
)
)
```

I think it would more more consistent. Please tell me what you think about this.

This is a breaking change so it needs to be executed with appropriate deprecation strategy and so on.