Revert "revert" to test toolchain change

[Kyle-Ye]

• Revert "Revert "Fix deprecated launch and launchPath API on Process""
• Revert "Revert "Fix deprecated readDataToEndOfFile API""
• Revert "Revert "Bump Swift version (Bump Swift version #4)" (Revert "Bump Swift version" #11)"

Bug/issue #, if applicable:

Summary

Revert #11 and #12 to test the change in the toolchain build.
@franklinsch

Checklist

Make sure you check off the following items. If they cannot be completed, provide a reason.

• Ran the ./bin/test script and it succeeded

[franklinsch]

Tracking testing this alongside Swift here: apple/swift#40031

[Kyle-Ye]

The test on Swift repo seems to be success. Could you please run test on this so that we can merge it if it success? @franklinsch

[franklinsch]

Now that the smoke tests pass, I also triggered toolchain builds in that PR.

@swift-ci please test

[Kyle-Ye]

Now that the smoke tests pass, I also triggered toolchain builds in that PR.

@swift-ci please test

Seems like both smoke tests and toolchain builds are passed. Could you review the change and merge it? @franklinsch

[Kyle-Ye]

@franklinsch Could we run test again and merge it?

[QuietMisdreavus]

@swift-ci Please test

[ethan-kusters]

@swift-ci Please test

[QuietMisdreavus]

It looks like the Swift toolchains built just fine with this PR, so let's go ahead and (re-)land it!