package.json: add missing transform variants for go.addTags

[skaldesh]

This simply allows in the settings.json or UI to use the missing 'lispcase', 'pascalcase' and 'keep'
transform options for the go.addTags command.

fixes #906

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Message from Hyang-Ah Hana Kim:

Patch Set 1: Run-TryBot+1 Code-Review+2 Trust+1

(1 comment)

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Patch Set 1:

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Patch Set 1: TryBot-Result+1

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Message from Hyang-Ah Hana Kim:

Patch Set 1:

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This PR is being closed because golang.org/cl/271357 has been merged.