cabal-3.14 v1-install expects Cabal file although not necessary

**Describe the bug**

I want to install many local packages at once, but cabal-3.14 refuses to do so, because there is no cabal description in the current package.

**To Reproduce**

This used to work:
```
/tmp$ cabal-3.12 v1-install pkg1/ pkg2/ pkg3/
```

But now I get:
```
/tmp$ cabal-3.14 v1-install pkg1/ pkg2/ pkg3/
...
Error: [Cabal-7654]
No cabal file found.
Please create a package description file .cabal
...
```

Start by reproducing the difference between cabal-3.12 and cabal-3.14 using v1-install with pkg1/, pkg2/, and pkg3/ from a directory without a Cabal file. Trace the v1-install entry point to see why it now requires a package description, then verify that installing multiple local packages works without one in the current directory.

Written by the indexing model from the issue text.