[TB 102] Attach vCard

[Frederick888]

Description

Support attachVCard.

A new header is needed.

And since

Note: If the value has not been modified, selecting a different identity will load the default value of the new identity.

By default the header can be something like

X-ExtEditorR-Attach-vCard: [false]

Then when parsing if we see X-ExtEditorR-Attach-vCard: true/false, we explicitly set the value.