Types cleanup

[janglad]

Reorganise and simplify types a bit.
Adds a simple test purely based on type perf and adds some quick type improvements, improves from

Files:              167
Lines:            63770
Identifiers:      53022
Symbols:          64204
Types:            15747
Instantiations:   71159
Memory used:    101694K
I/O read:         0.01s
I/O write:        0.00s
Parse time:       0.16s
Bind time:        0.05s
Check time:       0.19s
Emit time:        0.00s
Total time:       0.40s

to

Files:             167
Lines:           63759
Identifiers:     53126
Symbols:         59442
Types:           10848
Instantiations:  35410
Memory used:    94281K
I/O read:        0.01s
I/O write:       0.00s
Parse time:      0.15s
Bind time:       0.05s
Check time:      0.14s
Emit time:       0.00s
Total time:      0.35s

(majority is now coming from Zod)

Internal went from

Files:              251
Lines:            89319
Identifiers:      85550
Symbols:         146084
Types:            51212
Instantiations:  333672
Memory used:    178630K
I/O read:         0.01s
I/O write:        0.00s
Parse time:       0.25s
Bind time:        0.09s
Check time:       0.66s
Emit time:        0.00s
Total time:       1.00s

to

Files:              258
Lines:            89391
Identifiers:      85664
Symbols:         137527
Types:            43884
Instantiations:  246455
Memory used:    167708K
I/O read:         0.01s
I/O write:        0.00s
Parse time:       0.23s
Bind time:        0.08s
Check time:       0.58s
Emit time:        0.00s
Total time:       0.90s