Forbid duplicate namespace/static class members

[CountBleck]

(Barely) fixes #2793.

Changes proposed in this pull request: ⯈ Check diagnostics after initialize (VERY BAD) ⯈ Forbid duplicate namespace/static class members

Requiring the compiler to check diagnostics after initialize is VERY BAD, and ideally someone should find a way to prevent the compiler from attempting to compile the duplicate global (which it shouldn't see to begin with).

• [x] I've read the contributing guidelines
• [x] I've added my name and email to the NOTICE file

[CountBleck]

I wonder why do we need to split lots of test.

Yeah, checking diagnostics after initialize is VERY BAD.

[HerrCai0907]

Cannot detect this case

namespace A { export function foo(): i32 { return 1; } }

class A { static foo(): i32 { return 2; } }

export function _start(): void { trace("", 1, A.foo()); }

[CountBleck]

Cannot detect this case

That's not good at all.