Diagnostics are not shown for tests

[alexveden]

Describe the bug
Inline diagnostics are not shown in code for test files (dedicated @test modules).

Desktop (please complete the following information):

• OS: Linux
• Editor Vim
• Version LSP built from master

Additional context
I think the problem that tests are build with different command, to make the error message we need to run:

~/code/c3_advent ➜ c3c test --test
Error|c3_advent/test/test_foo.c3|7|32|Expected ';'

[pherrymason]

Diagnostics are fetched by compiling the code with c3, and displaying the errors it throws. Maybe the compiler is ignoring the tests and that's why no diagnostics are shown. Will invistigate