Support incompatible_strict_action_env

As of Bazel 9, `--incompatible_strict_action_env=true` is the default.

Almost everything works with that set, the one exception is Windows in a particular case. That particular case appears to be when the python program is a data dep of another binary, e.g. an sh_binary with a py_binary in data. What happens is the Bazel launcher can't find the python interpreter in runfiles, so falls back to looking for `python.exe` on `PATH`. When strict action env is enabled, the outer PATH isn't inherited, so python.exe can't be found, and thus the launcher fails to execute.

A direct execution of a python program is ok, since the runfiles structure is present enough that the bazel launcher can find the interpreter.

Other than moving away from the Bazel launcher, I don't see a way to solve this. We've wanted to stop using the bazel launcher anyways, so this isn't a big deal, this case just add additional pressure to do so.

Fundamentally, when a binary is running within another binary's runfiles, the logic to find things is a bit more convoluted. We can use RunEnvironmentInfo so that tests auto-inherit PATH, but this only helps tests. binaries-in-binaries or binaries-run-by-actions wouldn't be affected.

There are two workarounds:

* Set `--incompatible_strict_action_env=false` (restore non-strict env behavior, which includes PATH)
* Set `--action_env=PATH` (only inherit PATH for actions)

Beginne damit, den Windows-Fall mit Bazel 9 und aktivierter strikter Aktionsumgebung zu reproduzieren: ein sh_binary mit einem py_binary in data. Lies das Runfiles- und Interpreter-Suchverhalten des Bazel-Launchers und vergleiche es anschließend mit der direkten Python-Ausführung und dem RunEnvironmentInfo-Ansatz. Erledigt ist die Aufgabe, wenn die verschachtelte Binärdatei ihren Python-Interpreter finden kann, ohne die Vererbung von PATH oder den dokumentierten Workaround zu benötigen.

Vom Indexierungsmodell aus dem Issue-Text verfasst.