SCORU/Node: move store outside of protocol directories

Context

This MR makes the store be a common component to all rollup nodes. This an intermediate step in the protocol agnostic rollup node project.

With this MR, we ensure that the data written by a rollup node will be able to be read by another rollup node (for a different protocol) without ensuring that the code is synchronized.

Depends in !8830 (merged), !8824 (merged) and !8979 (merged).

Manually testing the MR

We can check that there is no migration necessary by running:

git checkout HEAD~2 # to remove the backport commits so that only alpha uses the common store.
dune exec tezt/tests/main.exe -- -f sc_rollup.ml -t 'Nairobi->Alpha: wasm_2_0_0 - node can read data after store migration' -v