parse-info-all bool

It would be cool if parts had a `parse-info-all` key which enables parsing all data it can find.

Currently a developer needs to list all appstream files AND then also set the common-id on the app. This seems excessive. Since appstream files have well known locations it'd be far easier to simply enable extracting all meta data from a part.

So

```
name: sampleapp-name
adopt-info: sampleapp

apps:
  sampleapp:
    command: sampleapp
    common-id: com.example.sampleapp

  otherapp:
    command: otherapp
    common-id: com.example.otherapp

  thirdapp:
    command: sampleapp
    common-id: com.example.thirdapp

parts:
  sampleapp:
    plugin: dump
    source: http://github.com/example/sampleapp.git
    parse-info: [usr/share/appdata/sampleapp.metainfo.xml,usr/share/appdata/otherapp.metainfo.xml,usr/share/appdata/thirdapp.metainfo.xml,usr/share/appdata/fourthapp.metainfo.xml]
```

to

```
name: sampleapp-name
adopt-info: sampleapp

apps:
  sampleapp:
    command: sampleapp
    common-id: com.example.sampleapp

  otherapp:
    command: otherapp
    common-id: com.example.otherapp

  thirdapp:
    command: sampleapp
    common-id: com.example.thirdapp

parts:
  sampleapp:
    plugin: dump
    source: http://github.com/example/sampleapp.git
    parse-info-all: true
```

If full extraction isn't viable for a given piece of software the developer may still opt to do the explicit list, so nothing is lost. In the event auto extraction will be the desired thing (which to me seems to be case for probably just about all FLOSS desktop application) the explicit listing is entirely superfluous.