Apache MINA sshd client: test reading encrypted ed25519 keys

Apache MINA sshd client: test reading encrypted ed25519 keys

Add encrypted ed25519 keys in the tests; sshd 2.2.0 can finally
decrypt encrypted new-style OpenSSH key files. (Needs the "unlimited
strength" JCE, which is the default since Java 8u161. On older JREs,
users should install the policy files available from Oracle.)

The "expensive" key added has been generated with OpenSSH's
ssh-keygen -t ed25519 -a 256, i.e., with 256 bcrypt KDF rounds
instead of the default 16. On my machine it takes about 2sec to
decrypt.

Bug: 541703
Change-Id: Id3872ca2fd75d8f009cbc932eeb6357d3d1f267c
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>