Results 31 issues of Maxim Zaks

This can be seen as a first step towards https://github.com/modularml/mojo/issues/1616

This PR is a reintroduction, because rebasing of PR #2109 went terribly wrong :). Sorry about that.

This proposal is based on discussion started in https://github.com/modularml/mojo/issues/1744

stdlib-proposal
mojo-repo

### Bug description While executing the code listed in reproduce section I experience a crash with following output: ``` Stack dump: 0. Program arguments: /home/maxim/.modular/pkg/packages.modular.com_mojo/bin/mojo /home/maxim/dev/mojo_hash/test_hashmap.mojo #0 0x000055abe8b7b937 (/home/maxim/.modular/pkg/packages.modular.com_mojo/bin/mojo+0x622937) #1...

bug
mojo-stdlib
mojo

Currently we go through all definitions in schema. We should rather collect definitions reachable from `root_type`. This will also enable support for #1

Currently the scoping is global but it should only work with `include` keyword.

The bugs are reproduced in the unit tests.

imported-internally
merged-internally
mojo-repo

This is a draft because although the code compiles 8 tests are failing. It might be due to compiler bug. The error messages are cryptic. I don't have the "Mojo"...