cue modules: move stdlib to pkg/alpha.dagger.io

In preparation for Europa, we will vendor multiple CUE modules:

- `pkg/alpha.dagger.io`: legacy non-europa packages
- `pkg/dagger.io`: core Europa packages
- `pkg/universe.dagger.io`: Europa universe

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

pkg/alpha.dagger.io/bats/tests/testfile/mods/bats-support/README.md

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+*__Important:__ `bats-core` has been renamed to `bats-support`. GitHub
+automatically redirects all references, e.g. submodules and clones will
+continue to work, but you are encouraged to [update][github-rename]
+them. Version numbering continues where `bats-core` left off.*
+
+[github-rename]: https://help.github.com/articles/renaming-a-repository/
+
+- - - - -
+
+# bats-support
+
+[![GitHub license](https://img.shields.io/badge/license-CC0-blue.svg)](https://raw.githubusercontent.com/ztombol/bats-support/master/LICENSE)
+[![GitHub release](https://img.shields.io/github/release/ztombol/bats-support.svg)](https://github.com/ztombol/bats-support/releases/latest)
+[![Build Status](https://travis-ci.org/ztombol/bats-support.svg?branch=master)](https://travis-ci.org/ztombol/bats-support)
+
+`bats-support` is a supporting library providing common functions to
+test helper libraries written for [Bats][bats].
+
+Features:
+- [error reporting](#error-reporting)
+- [output formatting](#output-formatting)
+
+See the [shared documentation][bats-docs] to learn how to install and
+load this library.
+
+If you want to use this library in your own helpers or just want to
+learn about its internals see the developer documentation in the [source
+files](src).
+
+
+## Error reporting
+
+### `fail`
+
+Display an error message and fail. This function provides a convenient
+way to report failure in arbitrary situations. You can use it to
+implement your own helpers when the ones available do not meet your
+needs. Other functions use it internally as well.
+
+```bash
+@test 'fail()' {
+  fail 'this test always fails'
+}
+```
+
+The message can also be specified on the standard input.
+
+```bash
+@test 'fail() with pipe' {
+  echo 'this test always fails' | fail
+}
+```
+
+This function always fails and simply outputs the given message.
+
+```
+this test always fails
+```
+
+
+## Output formatting
+
+Many test helpers need to produce human readable output. This library
+provides a simple way to format simple messages and key value pairs, and
+display them on the standard error.
+
+
+### Simple message
+
+Simple messages without structure, e.g. one-line error messages, are
+simply wrapped in a header and a footer to help them stand out.
+
+```
+-- ERROR: assert_output --
+`--partial' and `--regexp' are mutually exclusive
+--
+```
+
+
+### Key-Value pairs
+
+Some helpers, e.g. [assertions][bats-assert], structure output as
+key-value pairs. This library provides two ways to format them.
+
+When the value is one line long, a pair can be displayed in a columnar
+fashion called ***two-column*** format.
+
+```
+-- output differs --
+expected : want
+actual   : have
+--
+```
+
+When the value is longer than one line, the key and value must be
+displayed on separate lines. First, the key is displayed along with the
+number of lines in the value. Then, the value, indented by two spaces
+for added readability, starting on the next line. This is called
+***multi-line*** format.
+
+```
+-- command failed --
+status : 1
+output (2 lines):
+  Error! Something went terribly wrong!
+  Our engineers are panicing... \`>`;/
+--
+```
+
+Sometimes, for clarity, it is a good idea to display related values also
+in this format, even if they are just one line long.
+
+```
+-- output differs --
+expected (1 lines):
+  want
+actual (3 lines):
+  have 1
+  have 2
+  have 3
+--
+```
+
+<!-- REFERENCES -->
+
+[bats]: https://github.com/sstephenson/bats
+[bats-docs]: https://github.com/ztombol/bats-docs
+[bats-assert]: https://github.com/ztombol/bats-assert