Verify target_list and metric_list sources match

[jaredsnyder]

Fixes #173

• Add app_name attribute to Metric, Segement, etc classes so that sources from metric-hub can be checked
• exceptions raised for metric_list with multiple sources, target_list with multiple sources and when the sources between the two don't match
• Add warning for causes where there are metrics or segements not from metric-hub, and a metric has all 0s (which would indicate no support for the metric and therefore a mismatch between target and metric sources)

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 94.73684% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 80.64%. Comparing base (2df08a3) to head (79ff51b).

Files	Patch %	Lines
src/mozanalysis/sizing.py	93.33%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #220 +/- ## ========================================== + Coverage 78.88% 80.64% +1.76% ========================================== Files 23 23 Lines 1037 1054 +17 ========================================== + Hits 818 850 +32 + Misses 219 204 -15 ``` | [Flag](https://app.codecov.io/gh/mozilla/mozanalysis/pull/220/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mozilla) | Coverage Δ | | |---|---|---| | [project](https://app.codecov.io/gh/mozilla/mozanalysis/pull/220/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mozilla) | `80.64% <94.73%> (+1.76%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mozilla#carryforward-flags-in-the-pull-request-comment) to find out more.

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[m-d-bowerman]

The other thing that occurred to me is that using "source" in the warnings might be ambiguous -- users might take it to mean multiple DataSources are causing the warnings. I think using "app" might be more informative (e.g. segments and metric do not have a common app)

[jaredsnyder]

The other thing that occurred to me is that using "source" in the warnings might be ambiguous -- users might take it to mean multiple DataSources are causing the warnings. I think using "app" might be more informative (e.g. segments and metric do not have a common app)

Good catch, fixed it