FR: Support tools/bazel with extensions on Windows

[UebelAndre]

Projects which rely on the use of tools/bazel executable become extremely hard to maintain if windows support is needed there as there's not really an equivalent. The file is not naturally recognized as an executable and forcing all users to change this is very awkward and time consuming.

Instead of requiring an infrastructure change, Bazelisk could be updated to look for tools/bazel.ps1 and tools/bazel.bat on Windows. This would reduce maintenance for multi platform repos as the Bazel startup behavior can now be codified for Windows.