Multi-tenant Query Support

#### Is your feature request related to a problem? Please describe.

We're leveraging Loki, Mimir and Tempo within our OSS Stack, all of which are running in Multi-tenant mode, and all support Multi-tenant query support from Grafana (i.e, we can send multiple tenant IDs in the header). This is excellent for us, as it keeps our Grafana data sources nice and clean.

Pyroscope however seems to be the only Grafana product that doesn't support multi-tenant queries, meaning only one ID can be provided via Grafana. This means if we wanted to enable Multi-tenancy mode, we'd need to create several different data sources.

#### Describe the solution you'd like

Pyroscope to follow the same standard that Loki, Mimir and Tempo follows in terms of multi-tenant queries.

#### Describe alternatives you've considered

N/A

#### Additional context

N/A