Replace `unix.ByteSliceFromString` with own implementation

[brancz]

unix.ByteSliceFromString is behind a build tag, which causes it not to work under windows. I stumbled over this while trying to add windows as a build target in parca-debuginfo. As far as I can tell we should easily be able to replace this with our own implementation, which would allow us to support windows in parca-debuginfo.

[javierhonduco]

In the end, this was extracted to another project and I think it will be unlikely for the Agent to ever support windows. Should we close this issue or is it still something we want to work on?

[brancz]

This is not about the agent supporting windows, just some packages, so that dependents of those can at least compile on windows (obviously nothing ebpf related).

[javierhonduco]

That was my understanding, but should we close the issue or do you think that we still want to reuse this code?

[brancz]

We still active are using it in the parca-debuginfo component.