Supports multiple casting for variables using ContainerBuilder

[ticdenis]

Currently we have 3 options to cast variables using the ContainerBuilder:

# pyproject.toml

[tool.aiodi.variables]
# Get static text.
debug = "Text"
# Get as str a variable.
debug2 = "%var(debug)%"
# Cast to int an environment variable.
debug3 = "%env(int:APP_DEBUG, '1')%"

But we can not do:

# pyproject.toml

[tool.aiodi.variables]
# ...
debug4 = "%env(bool:int:APP_DEBUG, '1')%"

We've detected that this is a common operation so would be great have it integrate it on ContainerBuilder.