feat(mime): add gsheet default extension to map

[ziqq]

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Related issue #1198

[mosuem]

@ziqq - AFAIU, a .gsheet file cannot be opened directly. Would you mind explaining the use case of this?

[ziqq]

@ziqq - AFAIU, a .gsheet file cannot be opened directly. Would you mind explaining the use case of this?

Hello @mosuem, Yes i can. U can use mime.lookupMimeType to check files 'my_file.gsheet' of google sheets to get there mime type.

[mosuem]

This will probably be addressed in #2063, but leaving it open for now.