Don't insert imports when method calls are created through searcher

[mwu-tow]

Pull Request Description

When method call is inserted as a suggestion from searcher, the import of the relevant module won't be added anymore.
It is not needed and may cause trouble with name collisions, like #1145.
Issue #1178

Important Notes

Checklist

Please include the following checklist in your PR:

• The CHANGELOG.md was updated with the changes introduced in this PR.
• The documentation has been updated if necessary.
• All code conforms to the Rust style guide.
• All code has automatic tests where possible.
• All code has been profiled where possible.
• All code has been manually tested in the IDE.
• All code has been manually tested in the "debug/interface" scene.
• All code has been manually tested by the PR owner against our test scenarios.
• All code has been manually tested by at least one reviewer against our test scenarios.

[farmaazon]

Unfortunately, the reality is more complex than I expected. Actually there is scenario which works wrong with the current solution: press tab without any node selected, pick Table.new and press enter.

the new is a method, but it is a method of not imported module "Table". So actually we should skip importing only when we pick a method for this argument.

[kustosz]

@farmaazon @mwu-tow it's even more complex! Even if you have the this, some methods are extension methods. For an example, Json.to_table is a method in defined Table, even though Json comes from Base. So the rule for "import is not necessary" is:

1. The method being called comes from the same module as this. In this case, never import.
2. The method being called comes from a different module than this. Then check if the method's module is already imported and don't import if it aready is.

[farmaazon]

As for point 2: in scope of this task is only checking if we literally have the same import (as we do with other suggestions).

[kustosz]

@farmaazon sure, point 1 is the most important one, because it could lead you towards overoptimization – i.e. not importing extension methods, which would break programs (and not just make them ugly by too many imports)

[kustosz]

I have not read this code btw. it's very possible you've already taken everything into account :P Just saw this discussion and randomly commented

[farmaazon]

No, no, the point 1 in your comment is important (cc @mwu), and no, we don't handle it in our code.

[farmaazon]

Please, update the branch so I could easily test it with all new changes.