fix: missing walkContent on delete prompt

[mshanemc]

What does this PR do?

This bug happens when you use delete command with a remote-only piece of metadata. The confirmation prompt throws an error.

change how we determine "is it a sourceComponent?" so we don't get an unsafe walkContent() access.

[I tried to create a NUT for this but the interactive command framework won't allow commands with spaces in them, will resolve that separately in testkit]

What issues does this PR fix or reference?

forcedotcom/cli#2836
@W-15572525@

[cristiand391]

QA notes:

setup:
sf v2.38.7
created Wowowo apex class in org without retrieving it.

➜  dreamhouse-lwc git:(main) sf project delete source -m ApexClass:Wowowo
Error (10): c.walkContent is not a function or its return value is not iterable

✅ can delete remote-only metadata

➜  dreamhouse-lwc git:(main) sf project delete source -m ApexClass:Wowowo
 ›   Warning: @salesforce/plugin-deploy-retrieve is a linked ESM module and cannot be auto-transpiled. Existing compiled source will be used instead.
? This operation will delete the following metadata in your org:
ApexClass:Wowowo
Are you sure you want to proceed? no
Error (1): The request to delete metadata was canceled.

➜  dreamhouse-lwc git:(main) sf project delete source -m ApexClass:Wowowo
 ›   Warning: @salesforce/plugin-deploy-retrieve is a linked ESM module and cannot be auto-transpiled. Existing compiled source will be used instead.
? This operation will delete the following metadata in your org:
ApexClass:Wowowo
Are you sure you want to proceed? yes
*** Deleting with SOAP API ***
Status: In Progress | ████████████████████████████████████████ | 0/0 Components



Status: Succeeded | ████████████████████████████████████████ | 1/1 Components


=== Deleted Source

 FULL NAME TYPE      PROJECT PATH
 ───────── ───────── ────────────
 Wowowo    ApexClass