Make blob deferral period configurable

[preston-evans98]

Description

This PR allows makes the deferral period for blobs (DEFERRED_SLOTS_COUNT) configurable. While the change itself is very simple (1 line), fixing the tests required some more major modifications, because the old tests were predicated on a hard-coded delay period.

During this work, we:

1. Factor out initialization logic from the tests into a Runtime struct
2. Create a new BlobWithAppearance struct to track when a blob was posted on the (mock) DA layer and when it should be processed
3. Update existing tests to work with any DEFERRED_SLOTS_COUNT.
4. Remove the test deferred_blobs_are_first_after_preferred_sequencer_exit, since the invariant it enforced is not critical, and can no longer be provided when the DEFERRED_SLOTS_COUNT is not exactly equal to 1.

[codecov]

Codecov Report

Merging #1060 (747e43f) into nightly (606d7b8) will decrease coverage by 0.1%.
The diff coverage is 0.0%.

Files	Coverage Δ
...module-implementations/sov-blob-storage/src/lib.rs	97.5% <ø> (ø)
module-system/sov-modules-macros/src/manifest.rs	62.6% <ø> (-3.4%)	⬇️
module-system/sov-modules-api/src/lib.rs	89.5% <0.0%> (-1.8%)	⬇️
rollup-interface/src/state_machine/mocks/da.rs	81.1% <0.0%> (-1.3%)	⬇️

... and 2 files with indirect coverage changes