QtNetwork: Port from base64-encoded to binary storage.

At least the qssl_dhparams_default_base64 variable is stored in base-64 encoding. Since this ends up in the library, we waste a bit of space by using the 7-bit-clean base64 encoding instead of binary encoding.

Acceptance criteria:

• check all of QtNetwork sources for occurrences of base64-encoded string literals and port them to binary