server ssh UPDATE authentication with ECDSA keys

ECDSA keys can now be used both as a hostkey and for client
authentication. Three key pairs added for a new test.
diff --git a/tests/data/id_ecdsa256 b/tests/data/id_ecdsa256
new file mode 100644
index 0000000..6c01edb
--- /dev/null
+++ b/tests/data/id_ecdsa256
@@ -0,0 +1,9 @@
+-----BEGIN OPENSSH PRIVATE KEY-----
+b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAAAaAAAABNlY2RzYS
+1zaGEyLW5pc3RwMjU2AAAACG5pc3RwMjU2AAAAQQSGOtimPvmp8jbsK5kLto0HcgfaWGTB
+hBsn+c5deY0SQuzhj6vkxqkYMBTqAcpWLbj6xVhpTPs5LalDJ9ffuaj6AAAAqCh4tAQoeL
+QEAAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBIY62KY++anyNuwr
+mQu2jQdyB9pYZMGEGyf5zl15jRJC7OGPq+TGqRgwFOoBylYtuPrFWGlM+zktqUMn19+5qP
+oAAAAgBf3u7SBWmpDCm7esp1VnpoflXGytRAxp85nsb4Hhbd0AAAANcm9tYW5AcGN2YXNr
+bwECAw==
+-----END OPENSSH PRIVATE KEY-----
diff --git a/tests/data/id_ecdsa256.pub b/tests/data/id_ecdsa256.pub
new file mode 100644
index 0000000..169840d
--- /dev/null
+++ b/tests/data/id_ecdsa256.pub
@@ -0,0 +1 @@
+ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBIY62KY++anyNuwrmQu2jQdyB9pYZMGEGyf5zl15jRJC7OGPq+TGqRgwFOoBylYtuPrFWGlM+zktqUMn19+5qPo= test@libnetconf2
diff --git a/tests/data/id_ecdsa384 b/tests/data/id_ecdsa384
new file mode 100644
index 0000000..38211c7
--- /dev/null
+++ b/tests/data/id_ecdsa384
@@ -0,0 +1,10 @@
+-----BEGIN OPENSSH PRIVATE KEY-----
+b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAAAiAAAABNlY2RzYS
+1zaGEyLW5pc3RwMzg0AAAACG5pc3RwMzg0AAAAYQQSz1JFAWiAmtKwWSyCXdZUwNTS/m+c
+CpiUPC3vHZ82S1g2ihbQpN4IAIAAfRTER+rnV5/qClDmCjBsOSIaw86VcIykwAqcNy0x0i
+vGoyfpVL4/9CZfVSf/hwITxfbCK5MAAADYCMDKzgjAys4AAAATZWNkc2Etc2hhMi1uaXN0
+cDM4NAAAAAhuaXN0cDM4NAAAAGEEEs9SRQFogJrSsFksgl3WVMDU0v5vnAqYlDwt7x2fNk
+tYNooW0KTeCACAAH0UxEfq51ef6gpQ5gowbDkiGsPOlXCMpMAKnDctMdIrxqMn6VS+P/Qm
+X1Un/4cCE8X2wiuTAAAAMCpWDy26Bm4HFbLLgn/Jf8iJ/V5V5RXOnW994Jbh2w2b0gT9c5
+CfLHjENUhHF3zI9QAAAA1yb21hbkBwY3Zhc2tvAQID
+-----END OPENSSH PRIVATE KEY-----
diff --git a/tests/data/id_ecdsa384.pub b/tests/data/id_ecdsa384.pub
new file mode 100644
index 0000000..5dbf598
--- /dev/null
+++ b/tests/data/id_ecdsa384.pub
@@ -0,0 +1 @@
+ecdsa-sha2-nistp384 AAAAE2VjZHNhLXNoYTItbmlzdHAzODQAAAAIbmlzdHAzODQAAABhBBLPUkUBaICa0rBZLIJd1lTA1NL+b5wKmJQ8Le8dnzZLWDaKFtCk3ggAgAB9FMRH6udXn+oKUOYKMGw5IhrDzpVwjKTACpw3LTHSK8ajJ+lUvj/0Jl9VJ/+HAhPF9sIrkw== test@libnetconf2
diff --git a/tests/data/id_ecdsa521 b/tests/data/id_ecdsa521
new file mode 100644
index 0000000..1c43f0a
--- /dev/null
+++ b/tests/data/id_ecdsa521
@@ -0,0 +1,12 @@
+-----BEGIN OPENSSH PRIVATE KEY-----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+-----END OPENSSH PRIVATE KEY-----
diff --git a/tests/data/id_ecdsa521.pub b/tests/data/id_ecdsa521.pub
new file mode 100644
index 0000000..f49132a
--- /dev/null
+++ b/tests/data/id_ecdsa521.pub
@@ -0,0 +1 @@
+ecdsa-sha2-nistp521 AAAAE2VjZHNhLXNoYTItbmlzdHA1MjEAAAAIbmlzdHA1MjEAAACFBAF1Zs0nVxs5Vv2OSMVV7d5/yEzYlzcWCvHW5JxtaPNHIsUQttXGAx1CFVKGhsbKXbxLDi1A9cE+TaIm5nWKzwmTSADz0YmoosBsg7oxU5zpLDHeNH1U/SM7ERY3R236zBiRlg82yZIK1WXj3D6WL7vn1vmMhZQo1f6PAu5rQMajKTMjLg== test@libnetconf2