Promoted internal _tidy function to the utils module as dedent

[UebelAndre]

The functionality here would be useful elsewhere so I thought it should go in utils.bzl and I thought it'd be clearer to borrow the term dedent from python.

[hlopko]

Just a drive by - consider adding a test if you still have the behavior of the function cached in brain :) https://docs.bazel.build/versions/main/skylark/testing.html#for-testing-starlark-utilities

[UebelAndre]

Just a drive by - consider adding a test if you still have the behavior of the function cached in brain :) https://docs.bazel.build/versions/main/skylark/testing.html#for-testing-starlark-utilities

I'll add it to my list 😄

[UebelAndre]

Just a drive by - consider adding a test if you still have the behavior of the function cached in brain :) https://docs.bazel.build/versions/main/skylark/testing.html#for-testing-starlark-utilities

I feel like if this is going to be tested then it should go in bazel_skylib seems like functionality that would make folks happy. Or maybe even better, the doc attribute would be smart enough to perform a dedent, or maybe stardoc? It also feels kinda odd _tidy/dedent exists. We now pay a runtime cost to have the code look nicer? I'm all for maintainability but I think we could get away with writing maintainable code without dedent here. Thoughts? Should this be promoted? Should it be removed? Is this the thing that really needs tests (over others)?

[hlopko]

First of all, writing a test is independent from (and maybe a prerequisite for) later points.

After we have an implementation that is field tested and of good quality I think folks at https://github.com/bazelbuild/bazel-skylib might accept it. Historically they've been very pedantic and strict about what goes into Skylib and I don't know the exect policy. We should try.

If you want to automatically dedent the string in doc attribute, you'll have to fix stardoc (somewhere here: https://osscs.corp.google.com/bazel/bazel/+/master:src/main/java/com/google/devtools/build/skydoc/SkydocMain.java;l=103?q=SkydocMain&ss=bazel). I don't think the runtime cost of dedenting is significant enough to worry about it. And if it is, the short term fix is to extract doc strings to constants and not having extra indentation inside.