Iss031: Replace %>% with |> and drop magrittr dependency

[awunderground]

This is mostly find and replace. I had to make real changes to code because %>% and |> aren't strictly equivalent in the following:

• synth_spec() examples
• test-synthesize-factor-first.R
• test-enforce-schema.R
• construct_recipes()
• add_noise_kde.R

[jhseeman]

Changes look good, thanks for pre-specifying which files need substantive review. There are a few places where there's currently a merge conflict, do you think those require re-review after resolving?