Handle itemDefaults in CompletionList according to spec (#41187)

Closes https://github.com/zed-extensions/java/issues/101

Previously Zed did not handle resolving CompletionList with itemDefaults
correctly according to the
[LSP-Spec](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#:~:text=/**%0A%09%20*%20The%20edit%20text,%3F%3A%20string%3B).
When a `CompletionList` is provided by the server, that includes ranges
as `itemDefaults`, the field to use for the snippet to insert as
`newText` is in the `textEditText` field, with a fallback to `label` if
that does not exist (`insertText` is ignored).

Release Notes:

- Fixed Java language severs' completion defaults handling on Zed's side

crates/project/src/lsp_command.rs

@@ -2240,7 +2240,7 @@ impl LspCommand for GetCompletions {
                 let lsp_edit = lsp_completion.text_edit.clone().or_else(|| {
                     let default_text_edit = lsp_defaults.as_deref()?.edit_range.as_ref()?;
                     let new_text = lsp_completion
-                        .insert_text
+                        .text_edit_text
                         .as_ref()
                         .unwrap_or(&lsp_completion.label)
                         .clone();