Bugfix: Output ast for --ddump-initial-ast

[wanghuibin0]

I found that sail --ddump-initial-ast dumps nothing instead of the initial ast.
I think this behaviour confuses user so I make this PR to fix it.
This patch simply adds a print statement for --ddump-initial-ast at the beginning of function finalize_ast.

Could you help review this? @Alasdair

[Alasdair]

Well spotted, I suspect that option simply got left after a refactoring to the frontend removed the place it lived. We no longer construct a full AST before type checking each file (now each file has its own per-file AST), so it's not clear if the option even makes sense any more. I think finalize_ast might be a little late for a flag claiming to dump the initial AST though, which originally meant pre-type checking.

[github-actions]

Test Results

   12 files  ±0     24 suites  ±0   0s ⏱️ ±0s
  738 tests ±0    738 ✅ ±0  0 💤 ±0  0 ❌ ±0 
2 466 runs  ±0  2 465 ✅ ±0  1 💤 ±0  0 ❌ ±0 

Results for commit 66a6f5b. ± Comparison against base commit fd18b93.

[wanghuibin0]

OK, I see.

[wanghuibin0]

Does it make sense to remove the --ddump-initial-ast option?