feat: Add Azure instance identitity authentication (#1064)

This enables zero-trust authentication for Azure instances. Now
we support the three major clouds: AWS, Azure, and GCP 😎.

go.sum

@@ -558,6 +558,7 @@ github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMo
 github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
 github.com/fsnotify/fsnotify v1.5.1/go.mod h1:T3375wBYaZdLLcVNkcVbzGHY7f1l/uK5T5Ai1i3InKU=
 github.com/fsouza/fake-gcs-server v1.17.0/go.mod h1:D1rTE4YCyHFNa99oyJJ5HyclvN/0uQR+pM/VdlL83bw=
+github.com/fullsailor/pkcs7 v0.0.0-20190404230743-d7302db945fa h1:RDBNVkRviHZtvDvId8XSGPu3rmpmSe+wKRcEWNgsfWU=
 github.com/fullsailor/pkcs7 v0.0.0-20190404230743-d7302db945fa/go.mod h1:KnogPXtdwXqoenmZCw6S+25EAm2MkxbG0deNDu4cbSA=
 github.com/gabriel-vasile/mimetype v1.3.1/go.mod h1:fA8fi6KUiG7MgQQ+mEWotXoEOvmxRtOJlERCzSmRvr8=
 github.com/gabriel-vasile/mimetype v1.4.0/go.mod h1:fA8fi6KUiG7MgQQ+mEWotXoEOvmxRtOJlERCzSmRvr8=
@@ -1698,6 +1699,7 @@ go.etcd.io/bbolt v1.3.5/go.mod h1:G5EMThwa9y8QZGBClrRx5EY+Yw9kAhnjy3bSjsnlVTQ=
 go.etcd.io/etcd v0.5.0-alpha.5.0.20200910180754-dd1b699fc489/go.mod h1:yVHk9ub3CSBatqGNg7GRmsnfLWtoW60w4eDYfh7vHDg=
 go.mongodb.org/mongo-driver v1.5.1/go.mod h1:gRXCHX4Jo7J0IJ1oDQyUxF7jfy19UfxniMS4xxMmUqw=
 go.mongodb.org/mongo-driver v1.7.0/go.mod h1:Q4oFMbo1+MSNqICAdYMlC/zSTrwCogR4R8NzkI+yfU8=
+go.mozilla.org/pkcs7 v0.0.0-20200128120323-432b2356ecb1 h1:A/5uWzF44DlIgdm/PQFwfMkW0JX+cIcQi/SwLAmZP5M=
 go.mozilla.org/pkcs7 v0.0.0-20200128120323-432b2356ecb1/go.mod h1:SNgMg+EgDFwmvSmLRTNKC5fegJjB7v23qTQ0XLGUNHk=
 go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.31.0/go.mod h1:PFmBsWbldL1kiWZk9+0LBZz2brhByaGsvp6pRICMlPE=
 go.opentelemetry.io/otel v0.11.0/go.mod h1:G8UCk+KooF2HLkgo8RHX9epABH/aRGYET7gQOqBVdB0=