* copy_file: Add parameter to allow symlinks
This change adds a new parameter `allow_symlinks` to `copy_file` that
allows the action to create a symlink instead of doing an expensive
copy if the execution platform (host) allows it.
Updates #248
* Update docs
* Refactor `is_executable` into attribute
* Fix typo
* s/_impl/_copy_file_impl/
This PR adds two new rules: copy_file and
copy_xfile.
Both rules solve a common problem: to copy one
file to another location. The problem is routinely
solved using a genrule. That however requires
Bash, since genrules execute Bash commands.
Requiring Bash is a problem on Windows.
The new rules do not require Bash on Windows (only
on other platforms).
The only difference between the rules is that
copy_xfile creates an executable file while
copy_file doesn't.
See https://github.com/bazelbuild/bazel/issues/4319
