feat(rsc-auth): Implement serverStore to hold and pass req info to RSC

[dac09]

First pass at implementing a per-request store that allows:

• access to headers and cookies from requests in server components
• access to serverAuthState from server components
• maps serverAuthState updated from middleware to the the per request store

This PR also implements execution of middleware in the RSC handler. Note that this is done in a "good enough" way currently, because the RSC handler doesn't use Fetch requests (but everything else does)

Important things to note:

• the store is initialised again in the RSC worker, with the same values on each invocation of renderRsc
• we have not tested or tried in Dev because rw dev does not work in RSC yet
• we have not tested behaviour on initial SSR - because this is not implemented yet in RSC

[dac09]

Pulling out of draft @dthyresson - we still need to check with K6 or curl though if the store is isolated per request!