tree cab8b345390cae395c16801ba40761891c96af48
parent ddfc7d5c83cbde0dc4ec92bd0f0b8e24239a4fb2
author adonovan <adonovan@google.com> 1580240874 -0800
committer Copybara-Service <copybara-worker@google.com> 1580240951 -0800

bazel syntax: move Selector{List,Value} into lib.packages

(Second attempt at commit e8d482496f705304d21c938ec44dc578997ae942, rolled back in commit ed7d241f10c5ebbb7243a86479d2157b5d012b19,
because it broke Skydoc tests. The only new code is in SkydocMain.)

The Bazel 'select' function is no longer in Starlark.UNIVERSE.
It is pre-declared in all Bazel file environments (BUILD, .bzl, WORKSPACE).
This is a new category (though depset belongs in it too),
exposed as StarlarkLibrary.COMMON.

Also:
- make various methods private
- improve the annotation doc comment
- remove legacyNamed for select(x={...}).
  There are no uses in Google's depot.

A later change will merge Selector{List,Value} into a single data
type that represents a node in a binary tree whose branch nodes
are deferred '+' operations and whose leaves are dictionaries.
While removing what looked like unnecessarily qualified class
names, I discovered that BuildType.SelectorList is yet a third (!)
Starlark value class representing the same concept.

PiperOrigin-RevId: 291982062