Merge dynamic constant propagation into the constprop pass

[amarkdotdev]

Ordinary and dynamic constant propagation run the same rewrite; the dynamic path only loads JsirDynamicConstantPropagationAnalysis (prelude matching) first. There is no reason for two MLIR pass classes.

JsirConstantPropagationPass now handles both JsirTransformConfig kinds. PerformDynamicConstantPropagation lives next to PerformConstantPropagation, and the old dynamic pass .cc is gone. CLI names (constprop / dynconstprop) and proto fields are unchanged.

Fixes #19

[phisiart]

Thanks for the contribution! We currently only have a process to sync internal changes to github, but not the opposite direction. I'll need to manually create a matching internal change and merge your PR at just the right time :) This will take some time (maybe several days) to figure out, so please be patient in the meantime.

[amarkdotdev]

rebased onto latest main, kept the merged constprop dirs

[amarkdotdev]

fixed the ci failure

[amarkdotdev]

dirs are merged in 066225e, dynamic path always runs

[phisiart]

Hi, I'm trying to port this PR into an internal change, and the internal change leads to #158.

I realized that the PR created from the internal change can also list you as an author, so we can still properly credit the change to you. Do you mind if we submit #158 instead of this one? Thanks!

[amarkdotdev]

Re: directory merge — this is already done on merge-constprop-passes:

• maldoca/js/ir/analyses/{constant_propagation,dynamic_constant_propagation} → single constant_propagation/ directory (dynamic analysis files live alongside the static ones)
• maldoca/js/ir/transforms/{constant_propagation,dynamic_constant_propagation} → single constant_propagation/ directory (dynamic tests merged under dynamic_tests/)
• The dynamic analysis path always runs; without a prelude it falls back to the non-dynamic behavior

CI is green on the current branch.

Re: #158 — yes, that's fine with me. Submitting via the internal change path in #158 works as long as authorship credit is preserved as you mentioned. Happy to close #146 once #158 lands.