TESTS: jws: register a unittest for jwk

TESTS: jws: register a unittest for jwk

Add a way to test the jwk converter in the unit test system

    $ make TARGET=linux-glibc USE_OPENSSL=1 CFLAGS="-DDEBUG_UNIT=1"
    $ ./haproxy -U jwk foobar.pem.rsa
    {
        "kty": "RSA",
        "n":   "...",
        "e":   "AQAB"
    }
    $ ./haproxy -U jwk foobar.pem.ecdsa
    {
        "kty": "EC",
        "crv": "P-384",
        "x":   "...",
        "y":   "..."
    }

This is then tested by a shell script:

    $ HAPROXY_PROGRAM=${PWD}/haproxy tests/unit/jwk/test.sh
    + readlink -f tests/unit/jwk/test.sh
    + BASENAME=/haproxy/tests/unit/jwk/test.sh
    + dirname /haproxy/tests/unit/jwk/test.sh
    + TESTDIR=/haproxy/tests/unit/jwk
    + HAPROXY_PROGRAM=/haproxy/haproxy
    + mktemp
    + FILE1=/tmp/tmp.iEICxC5yNK
    + /haproxy/haproxy -U jwk /haproxy/tests/unit/jwk/ecdsa.key
    + diff -Naurp /haproxy/tests/unit/jwk/ecdsa.pub.jwk /tmp/tmp.iEICxC5yNK
    + rm /tmp/tmp.iEICxC5yNK
    + mktemp
    + FILE2=/tmp/tmp.EIrGZGaCDi
    + /haproxy/haproxy -U jwk /haproxy/tests/unit/jwk/rsa.key
    + diff -Naurp /haproxy/tests/unit/jwk/rsa.pub.jwk /tmp/tmp.EIrGZGaCDi
    + rm /tmp/tmp.EIrGZGaCDi

    $ echo $?
    0