Improve error message for missing dependencies in packages (JuliaLang#58878)

Author: eschnett

base/loading.jl

@@ -2378,7 +2378,8 @@ function __require(into::Module, mod::Symbol)
             else
                 manifest_warnings = collect_manifest_warnings()
                 throw(ArgumentError("""
-                Package $(where.name) does not have $mod in its dependencies:
+                Cannot load (`using/import`) module $mod into module $into in package $(where.name)
+                because package $(where.name) does not have $mod in its dependencies:
                 $manifest_warnings- You may have a partially installed environment. Try `Pkg.instantiate()`
                   to ensure all packages in the environment are installed.
                 - Or, if you have $(where.name) checked out for development and have