gopls/internal/golang: improve extract variable edits

[gayanper]

The previous implementation use common edits to support both scenarios
where a assignment/declaration exist and did not exist. This cause a
additional text edit with lhs values in the new line when the
extraction was done on a expression which was not part of a
assignment/declaration. The new changes address this scenarios by
computing edits based on the scenario to avoid the additional lhs in
new line when extracted expression is not part of a
assignment/declaration.

Fixes golang/tools#65944

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[gopherbot]

Message from Gopher Robot:

Patch Set 1:

(1 comment)

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Patch Set 1:

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[gopherbot]

This PR (HEAD: ebc1a8b) has been imported to Gerrit for code review.

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[gopherbot]

Message from Gayan Perera:

Patch Set 3:

(1 comment)

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