Add initial Microsoft Teams support

Documentation on https://github.com/42wim/matterbridge/wiki/MS-Teams-setup

vendor/github.com/yaegashi/msgraph.go/beta/AttachmentModel.go

@@ -0,0 +1,21 @@
+// Code generated by msgraph-generate.go DO NOT EDIT.
+
+package msgraph
+
+import "time"
+
+// Attachment undocumented
+type Attachment struct {
+	// Entity is the base model of Attachment
+	Entity
+	// LastModifiedDateTime undocumented
+	LastModifiedDateTime *time.Time `json:"lastModifiedDateTime,omitempty"`
+	// Name undocumented
+	Name *string `json:"name,omitempty"`
+	// ContentType undocumented
+	ContentType *string `json:"contentType,omitempty"`
+	// Size undocumented
+	Size *int `json:"size,omitempty"`
+	// IsInline undocumented
+	IsInline *bool `json:"isInline,omitempty"`
+}