Feature Request: Get size for specific module only

**Is your feature request related to a problem? Please describe.**
I'd like to track the module size over time. However using something like `--modules=module1` with the `get-size` will give me size of `base` + `module1`. Is it possible to add a flag to grab size of exactly one module.

**Describe the solution you'd like**
Possibly add a flag like `--exact` that would only include the APKs for the specified modules. For example:
`--modules=base,module1 --exact` return size for `base.apk` + `module1.apk` (equivalent to `--modules=base,module1` or `--modules=module1`)
`--modules=module1 --exact` would return `module1.apk`