[Feature] Enable import of pure functions in circular dependency import

[Ph0enixKM]

Is your feature request related to a problem? Please describe.
This problem enables the import of pure functions even if there is an import dependency cycle. This issue implements a logic that works under the hood and has no impact on syntax.

• If all imported functions are pure, then import is pure. This means that we can import pure functions from file that normally would create a dependency cycle.
• Pure import is separated from regular import in import_cache.
• Pure functions are placed before all the generated bash code.
• Pure functions are the ones that don't depend on external variables nor functions.

Describe the solution you'd like

• Write a way to detect if function is pure and persist that to the cache
• If function is defined, we have to compile it so that we know if it's pure. As for generic functions we can assume default type to be Text
• Create a way to mark file that was imported purely in the import_cache.
• Compile the pure functions first before resolving the usual import topology

Describe alternatives you've considered
N/A

Additional context
Let's say that we have file main.ab

import { bar } from "other.ab"

fun aux() {
	echo bar()
}

fun foo() {
	echo "foo"
}

and file other.ab.

import { foo } from "main.ab"

fun bar() {
	echo foo() + "bar"
}

Even though there is an import cycle, the functions could be imported perfectly fine since foo is a pure function that does not rely on the context of the file it was created in.