fix(initrd): Several small fixes

[craciunoiuc]

Prerequisite checklist

• Read the contribution guidelines regarding submitting new changes to the project;
• Tested your changes against relevant architectures and platforms;
• Ran make fmt on your commit series before opening this PR;
• Updated relevant documentation.

Description of changes

GitHub-Fixes: #904

[craciunoiuc]

PS C:\Users\Cezar\kraftkit> go test ./initrd
--- FAIL: TestNewFromDirectory (0.03s)
    directory_test.go:83: Encountered unexpected file in cpio archive: testdata/rootfs
    directory_test.go:94: file [/entrypoint.sh]: got size 27, expected 25
    directory_test.go:94: file [/etc/app.conf]: got size 18, expected 16
    directory_test.go:88: file [/lib/libtest.so.1]: got mode 0100000, expected 0120000
    directory_test.go:91: file [/lib/libtest.so.1]: got linkname "", expected "libtest.so.1.0.0"
    directory_test.go:94: file [/lib/libtest.so.1]: got size 16, expected 0
    directory_test.go:94: file [/lib/libtest.so.1.0.0]: got size 10, expected 9

@antoineco The tests still fail on windows but now I think this is because of something else:

• It appends \CR when reading files, that's why each line is an extra line
• Links behave differently within Windows

[antoineco]

@craciunoiuc good thing that the tests caught that. In the current state of things, an image created on Windows won't run with Unikraft.

[craciunoiuc]

No fears my son ✝️ push the Merge button

(also add your approved-by in there)