Missing MIME Format Path for SendMail and CreateReply actions

[peombwa]

The API supports sending mail using MIME format by specifying the MIME content as a base64-encoded string in the request body as shown in the example at https://learn.microsoft.com/en-us/graph/api/user-sendmail?view=graph-rest-1.0&tabs=powershell#example-4-send-a-new-message-using-mime-format:

POST https://graph.microsoft.com/v1.0/me/sendMail
Content-type: text/plain

RnJvbTogQWxleCBXaWxiZXIgPEFsZXhXQGNvbnRvc28uY29tPgpUbzogTWVnYW4gQm93ZW4gPE1l
Z2FuQkBjb250b3NvLmNvbT4KU3ViamVjdDogSW50ZXJuYWwgUmVzdW1lIFN1Ym1pc3Npb246IFNh
bGVzIEFzc29jaWF0ZQpUaHJlYWQtVG9waWM6IEludGVybmFsIFJlc3VtZSBTdWJtaXNzaW9uOiBT
YWxlcyBBc3NvY2lhdGUKVGhyZWFkLUluZGV4OiBjb2RlY29kZWNvZGVoZXJlaGVyZWhlcmUKRGF0
ZTogU3VuLCAyOCBGZWIgMjAyMSAwNzoxNTowMCArMDAwMApNZXNzYWdlLUlEOgoJPE1XSFBSMTMw
MU1CMjAwMDAwMDAwRDc2RDlDMjgyMjAwMDA5QUQ5QTlASFdIUFIxMzAxTUIwMDAwLmNvZGVudW0u
cHJvZC5vdXRsb29rLmNvbT4KQ29udGVudC1MYW5ndWFnZTogZW4tVVMKWC1NUy1IYXMtQXR0YWNo
OgpYLU1TLVRORUYtQ29ycmVsYXRvcjoKWC1NUy1Fe

This representation is currently absent in the metadata which leads to downstream tooling and SDKs not generating paths for sending mail in MIME format. Here is the current representation of the OData action in metadata:

<Action Name="sendMail" IsBound="true">
  <Parameter Name="bindingParameter" Type="graph.user" />
  <Parameter Name="Message" Type="graph.message" Nullable="false" />
  <Parameter Name="SaveToSentItems" Type="Edm.Boolean" />
</Action>

Originally reported at microsoftgraph/msgraph-sdk-powershell#844.

[andrueastman]

Including the createReply action as well here.

https://learn.microsoft.com/en-us/graph/api/message-createreply?view=graph-rest-1.0&tabs=csharp#example-2-create-a-draft-message-in-mime-format-to-reply-to-an-existing-message

Originally reported at microsoftgraph/msgraph-sdk-dotnet#1802