Fixing Transitive Runfiles

[CauhxMilloy]

Updating the call to ctx.runfiles() in the bats_test() impl function. Instead of setting transitive_files to the files of ctx.attr.data and ctx.attr.dep, this PR uses default_runfiles.files for deps. The effect is that all runfiles (not only the immediate outputs) of deps will be copied into the bats_test target's runfiles.

The existing issue can be shown when a bats_test() target's dep target contains data, it does not get copied over. Consider:

cc_binary(
  name = "tool",
  srcs = "main.cc",
  data = ["tool_config.txt"],
)
bats_test(
  name = "tool_test",
  deps = [":tool"],
)

In this example, the bats_test needs the :tool target (to run tests against the binary). With the current implementation, it will only get the binary. The data ("tool_config.txt") will not be copied over into the test runfiles. This is not only inconsistent (since running :tool would always have the file present), but it may (depending on the binary's functionality) cause the binary to no longer run correctly, as it depends on that file to be present. data files are also missing from any further transitive dependencies further in the build DAG.

This issue is also present with sh_binary for both data and deps, due to both attributes being treated as the same. This causes any transitive scripts (i.e. deps) to be missing in the bats_test runfiles.

This PR fixes this by gathering all runfiles (which includes deps and data + transitives) for each dep defined. This PR does not modify how data is processed, as data is moreso intended to explicitly list files (or filegroups) instead of targets (which would have their own deps/data). This distinction is merely a semantic one and data could also be processed in the same way in the future, if desired.