testdata: add a few more testkit vectors

cmd/age/testdata/fail_bad_hmac.age

@@ -1,5 +0,0 @@
-age-encryption.org/v1
--> X25519 i6JOY3uvMdBuEybYbTp3ECFsOPEY/A3lJY1l0Qv2NC4
-cD7VpfIOchU6ZjAccEjlPCNSOdJvVkxZPSf+7XS1YhY
---- 1111111111111111111111111111111111111111111
-<EFBFBD>-\<5C>P9<50><39>0<1D>hń<68><C584>Tt<54>|:٘<>#&R<>r<EFBFBD> <20><>

cmd/age/testdata/fail_large_filekey_x25519.age

@@ -1,6 +0,0 @@
-age-encryption.org/v1
--> X25519 UkSgrxSETNpdkHY8EwiiRivqks2QJLUzsNsVjUTDcmw
-8yB9TqsBo4Ypchw07AtemV5TW4sGwyPDPMIfRg8Ve8rbDXt4tCwnnKcMq2K6aoqx
-
---- vUhLU0U9Dc8YhbKy4SxKuq0iSqqjBWGnHfZG+9+O4v4
-ﾀｹ<EFBFBD><EFBFBD>ｲ€hｴW諾餞I暠fｯﾆ<EFBDAF>索Q;ﾐRh皷w

cmd/age/testdata/good_empty_payload.age

@@ -1,5 +0,0 @@
-age-encryption.org/v1
--> X25519 JRosIz2avWchP2qSL6wF6U7uzD6kDuJXDbZvN1MOGmo
-KpIQxpkbBDHqp+JsHLiTy2d5RYRwp2qzvUrAe0aDOnk
---- orVjbqbzm8U3S9njAs53o4PFi1wK39fIQQ4gRj3i7IU
-„Ïgñ¾<>Ô0‡‘µÆN¢'jûöao<61>¹&æT

cmd/age/testdata/good_empty_recipient_body.age

@@ -1,7 +0,0 @@
-age-encryption.org/v1
--> X25519 alRneDshIh43nwyD5+fhuTD5TReSn88f2us4hzZPyzU
-pGduNK5MUhnuzMxW0qbZnC2k7mRzz69bbJpKQrRc7uc
--> A7)h-grease !,_
-
---- 5bA0uXjBxI6wuI5SseCRgD5/G8LkSVISRe/hnrQMb9s
-¦Ã 1‘·¬Žä6_RÙäÚ…›…U<ï1ús®ÿ?`Ö+–’$§HÖW‚v?w8ZW