CustomDebugInformation: decode EmbeddedSource, split columns

[fowl2]

Problem

Embedded source custom debug info displays as hex:

Solution

Decode it:

Also:

• split "Kind" (combined Guid heap offset, Guid, description) into Kind, KindGUID and KindString, respecively
• add "Info" with embedded source format and length
• add ValueLength with blob length

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Future: It would probably be nice if there was some way to select/override the decoding method (eg. force a specific character encoding / base64 / hex), open in a tab, add syntax highlighting, save the raw content, etc.