LSP Completion: use textEdit.newText as a workaround
Some LSP server implementation, such as rust-analyzer 2021-11-01,
do not use insertText
field, but uses textEdit
.
Since we don't have real support for textEdit
(see Commit 831a0069),
the field textEdit.newText
is used as a workaround here to prevent
a worse fallback to use label as the inserted text.