Do not create a model reference for inline editors

[tsmaeder]

What it does

Fixes #14924

How to test

Make sure all our uses of text editors (regular editors, notebook, output view, chat input) work as expected. Make sure the original problem (#14880) stays fixed on Linux.

Follow-ups

We should investigate the root causes both in the chat input widget layout as well as our text model management that caused this problem.

Breaking changes

• This PR introduces breaking changes and requires careful review. If yes, the breaking changes section in the changelog has been updated.

Attribution

Contributed on behalf of STMicroelectronics

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[sdirix]

I did not see any regression, the original issue is still fixed and the chat input works again. Thanks!

[tsmaeder]

The error in the failing PR check is

@theia/core: free(): double free detected in tcache 2
@theia/core: node:internal/errors:540
@theia/core:       throw error;
@theia/core:       ^
@theia/core: TypeError [ERR_INVALID_ARG_TYPE]: The "code" argument must be of type number. Received type string ('128SIGABRT')
@theia/core:     at process.set [as exitCode] (node:internal/bootstrap/node:123:9)
@theia/core:     at ChildProcess.<anonymous> (/home/runner/work/theia/theia/node_modules/foreground-child/index.js:63:22)
@theia/core:     at ChildProcess.emit (node:events:524:28)
@theia/core:     at maybeClose (node:internal/child_process:1101:16)
@theia/core:     at ChildProcess._handle.onexit (node:internal/child_process:304:5) {
@theia/core:   code: 'ERR_INVALID_ARG_TYPE'
@theia/core: }

I've seen this error before and it eventually goes away when trying long enough. It is highly unlikely that it is related to this PR.