A stable API of compiling module as you type

Nobody has claimed this yet.

In release 7.2, we merged two internal flags into a single one, `-bs-no-builtin-ppx-ml` and `-bs-no-builtin-ppx-mli` are removed to use `-bs-no-builtin-ppx`, this unfortunately broken RLS again

https://github.com/jaredly/reason-language-server/blob/master/src/analyze/Packages.re#L215

Curious why that flag is used?

There are some more reliable ways to get such command line flags, for example:

```
c0003$bsb -- -t commands src/Index-ReasonReactExamples.cmj
/Users/hongbozhang/.npm-global/lib/node_modules/bs-platform/darwin/bsc.exe -color always -bs-jsx 3 -bs-super-errors -bs-no-version-header -o src/Index.reast -bs-syntax-only -bs-binary-ast /Users/hongbozhang/git/c0003/src/Index.re
/Users/hongbozhang/.npm-global/lib/node_modules/bs-platform/darwin/bsb_helper.exe -hash cc2c292add0cc18fbea75e77d145581f -bs-ns ReasonReactExamples -g 0 src/Index.reast
/Users/hongbozhang/.npm-global/lib/node_modules/bs-platform/darwin/bsc.exe -bs-package-name reason-react-examples -bs-ns ReasonReactExamples -bs-package-output commonjs:src -color always -bs-suffix -I . -I src/ReducerFromReactJSDocs -I src/ReasonUsingJSUsingReason -I src/BlinkingGreeting -I src/FetchedDogPictures -I src -I /Users/hongbozhang/git/c0003/node_modules/reason-react/lib/ocaml -bs-super-errors -bs-no-version-header -o src/Index-ReasonReactExamples.cmj src/Index.reast
```

I would like to help provide a more stable way of doing such things, let me know how I can help here

You can also get a list of targets here:
```
c0003$bsb -- -t targets
src/Index-ReasonReactExamples.cmj: ml_cmj_cmi
src/Index-ReasonReactExamples.cmi: ml_cmj_cmi
/Users/hongbozhang/git/c0003/src/Index.bs.js: ml_cmj_cmi
src/ExampleStyles-ReasonReactExamples.cmj: ml_cmj_cmi
src/ExampleStyles-ReasonReactExamples.cmi: ml_cmj_cmi
/Users/hongbozhang/git/c0003/src/ExampleStyles.bs.js: ml_cmj_cmi
src/FetchedDogPictures/FetchedDogPictures-ReasonReactExamples.cmj: ml_cmj_cmi
src/FetchedDogPictures/FetchedDogPictures-ReasonReactExamples.cmi: ml_cmj_cmi
/Users/hongbozhang/git/c0003/src/FetchedDogPictures/FetchedDogPictures.bs.js: ml_cmj_cmi
src/BlinkingGreeting/BlinkingGreeting-ReasonReactExamples.cmj: ml_cmj_cmi
src/BlinkingGreeting/BlinkingGreeting-ReasonReactExamples.cmi: ml_cmj_cmi
/Users/hongbozhang/git/c0003/src/BlinkingGreeting/BlinkingGreeting.bs.js: ml_cmj_cmi
src/ReasonUsingJSUsingReason/ReasonReactCard-ReasonReactExamples.cmj: ml_cmj_cmi
src/ReasonUsingJSUsingReason/ReasonReactCard-ReasonReactExamples.cmi: ml_cmj_cmi
/Users/hongbozhang/git/c0003/src/ReasonUsingJSUsingReason/ReasonReactCard.bs.js: ml_cmj_cmi
src/ReasonUsingJSUsingReason/ReasonUsingJSUsingReason-ReasonReactExamples.cmj: ml_cmj_cmi
src/ReasonUsingJSUsingReason/ReasonUsingJSUsingReason-ReasonReactExamples.cmi: ml_cmj_cmi
/Users/hongbozhang/git/c0003/src/ReasonUsingJSUsingReason/ReasonUsingJSUsingReason.bs.js: ml_cmj_cmi
src/ReducerFromReactJSDocs/ReducerFromReactJSDocs-ReasonReactExamples.cmj: ml_cmj_cmi
src/ReducerFromReactJSDocs/ReducerFromReactJSDocs-ReasonReactExamples.cmi: ml_cmj_cmi
/Users/hongbozhang/git/c0003/src/ReducerFromReactJSDocs/ReducerFromReactJSDocs.bs.js: ml_cmj_cmi
ReasonReactExamples.cmi: build_package
```

Start in src/analyze/Packages.re around line 215 and inspect how the removed compiler flags are passed to RLS. Use the provided bsb -- -t commands and targets examples to compare available compiler invocations and targets. Done means RLS uses a stable way to obtain compiling-module command-line information after the release 7.2 flag change.

Written by the indexing model from the issue text.