fix(@angular-devkit/build-angular): improve package deep import Sass index resolution in esbuild plugin

[clydin]

When resolving Sass imports in the experimental esbuild-based browser application builder's Sass plugin, previously imported modules are used as the base for resolution attempts to workaround the lack of the importer file provided by Sass. When attempting to resolve a deep import into a package (including the potential Sass index files), these previously imported modules also need to be checked. This is particularly relevant when using the Yarn PnP or pnpm package managers which enforce strict dependency resolution.

Fixes #24271