Expose some form of the metric definition when using a metric

Nobody has claimed this yet.

**What problem will this feature request solve?**
If a user doesn't have permissions to edit the metric definition but can still view/use it, there's no way for the user to be able to see what is the underlying definition of that metric. You can only see the name of it, with no way to see how the metric is calculated.

**Describe the solution you'd like.**
Expose a way to show the underlying formula of a metric so that users can better understand what the metric is.

I suppose metric creators could also be more explicit in their metric title and descriptions to give users a better idea of what the metric is.
Even for the metrics creator themselves, being able to see the metric definition without needing to click the three dots and be taken to a different page would greatly improve the experience of these metrics being easier to use (by showing what it means right next to where you use it).

**How does this feature request impact you?**
Metrics are a source of truth for KPIs for this customer, and currently, this limitation makes it hard for the organization to use them effectively.

**Additional information**
Customer request

Related https://github.com/metabase/metabase/issues/68006

No implementation files or tests are named. Start by reviewing related issue #68006 and the existing metric-use experience, then determine where metric definitions are displayed and how view permissions apply. Done means users can inspect a metric's underlying formula without needing edit access or navigating away.

Written by the indexing model from the issue text.