Fix PATH changes not triggering REPL reconfiguration (#2015)

When a user's PATH environment variable changes between Cabal commands,
the environment in the REPL becomes incorrect. This occurs because
during initial package configuration, the current PATH is captured via
`programSearchPathAsPATHVar` and then stored in the `programOverrideEnv`
field of a ConfiguredProgram. These `ConfiguredProgram`s are subsequently
serialized into the setup-config file, effectively baking in the PATH
environment from the time of configuration.

The issue manifests when `PATH` is updated after initial configuration.
Although the solver re-runs when detecting `PATH` changes, the
`dryRunLocalPkg` function examines `ElaboratedConfiguredPackage` and
incorrectly determines that nothing has changed that would require
reconfiguration. This decision is incorrect because `setup-config` now
contains a stale reference to the original `PATH` value, which no longer
matches the current environment.

To fix this problem, we need to store the `ConfiguredProgram`s directly in
`ElaboratedConfiguredPackage`. This approach will ensure that when `PATH`
changes, the `ConfiguredProgram`s will also change, properly triggering
reconfiguration. While this solution will cause more recompilations when
`PATH` changes, it guarantees that the correct environment is always used
during builds and REPL sessions.

An alternative approach would be to stop baking the `PATH` variable into
the environment of programs, but this would require more substantial
changes to how Cabal manages environment variables.

Fixes #2015