[Bug]: entry_point doesn't override webpack.config if the config contains `entry: {}`

### What happened?

If your webpack config contains `entry: {}` being set, the rule will not override even if you pass `entry_point`. You need to pass args `--entry-reset` and then entry points you care about to do so. This also has the side effect of exposing that `args` doesn't interpolate and expand `format` strings. #144 was an attempt to fix this partially, but not a good one.

https://webpack.js.org/api/cli/#entry

### Version

Development (host) and target OS/architectures:

Output of `bazel --version`:
6.4.0

Version of the Aspect rules, or other relevant rules from your
`WORKSPACE` or `MODULE.bazel` file:

Language(s) and/or frameworks involved:

### How to reproduce

```shell
Create a webpack config with `entry` set
Set a rule that overrides entry with `entry_point`
Bazel run or build that target and see the entry point is not overridden

Pass `args` to the rule that then sets `--entry-reset --entry=` and see it work
```

### Any other information?

_No response_

Start by reproducing the issue with a webpack config containing `entry: {}` and a rule using `entry_point`, then compare it with explicit `--entry-reset` and `--entry` arguments. Trace how the rule constructs webpack CLI arguments, including `args` format interpolation. Done means `entry_point` overrides the configured entry without manual reset arguments and existing argument handling remains correct.

Written by the indexing model from the issue text.