Add @ember/string dependency to package.json

[NullVoxPopuli]

Probably solves #1202

[HEYGUL]

I was about to do the same PR :-)
Thank you for this job.
Any chance to have a release soon embedding this change ?

[mixonic]

I re-ran the failing tests here once or twice and they seem persistent. I expect they need debugging- Either something in the change itself or possibly in the way the test scenarios are setup in Ember try is not as is expected.

[NullVoxPopuli]

@mixonic I believe this is a floating dep issue:

not ok 1 Chrome 142.0 - [undefined ms] - Global error: Uncaught Error: The tests file was not loaded. Make sure your tests index.html includes "assets/tests.js". at http://localhost:7357/119130529214/tests/index.html?hidepassed, line 80
    ---
        browser log: |
            {"type":"error","text":"Uncaught Error: The tests file was not loaded. Make sure your tests index.html includes \"assets/tests.js\". at http://localhost:7357/119130529214/tests/index.html?hidepassed, line 80\n","testContext":{}}
    ...

if you re-roll the lockfile on a separate branch, I would expect something similar to appear

[HEYGUL]

Hi @mixonic
Do you need any help to push this work to release ?
I'll be glad to help you.