Insert a test function for the storage and tests for Memory, ScyllaDb and DynamoDb. (#4821)

## Motivation

The `linera-storage` is a critical part of `linera`. However, we do not
have unit tests for the storage
functionality, even if it is very important. Instead, the tests are done
in `linera-views`, in the `end-to-end`
tests and other tests.

## Proposal

Introduce a function that takes a storage and does the tests.
Introduce three separate functions for the memory, DynamoDb, and
ScyllaDb.


## Test Plan

The PR introduces some tests.
The memory tests are immediate, the DynamoDb takes 0.3s, and the
ScyllaDb 0.69s.

## Release Plan

- Nothing to do / These changes follow the usual release cycle.
There is no need to put it on TestNet Conway.

## Links

None.

Author: MathieuDutSik

Cargo.lock

@@ -19,6 +19,8 @@ revm = ["linera-execution/revm"]
 test = ["linera-execution/test", "linera-views/test"]
 wasmer = ["linera-execution/wasmer"]
 wasmtime = ["linera-execution/wasmtime"]
+scylladb = ["linera-views/scylladb"]
+dynamodb = ["linera-views/dynamodb"]
 metrics = [
     "linera-base/metrics",
     "linera-chain/metrics",
@@ -50,6 +52,9 @@ tracing.workspace = true
 [dev-dependencies]
 anyhow.workspace = true
 linera-storage = { path = ".", default-features = false, features = ["test"] }
+test-case.workspace = true
+test-log = { workspace = true, features = ["trace"] }
+tokio.workspace = true
 
 [build-dependencies]
 cfg_aliases.workspace = true