Add DB crate that store and validator use

[sergerad]

As per comment:

I don't think validator should depend on the store. If there is some common functionality needed by both, I think we should move this to the utils crate (or maybe a new crate).

Must be done after #1614 is merged.

[sergerad]

Planning to pull out the following:

➜ grep -r 'miden_node_store' ./crates/validator
./crates/validator/src/block_validation/mod.rs:use miden_node_store::{DatabaseError, Db};
./crates/validator/src/server/mod.rs:use miden_node_store::Db;
./crates/validator/src/db/models.rs:use miden_node_store::SqlTypeConvert;
./crates/validator/src/db/mod.rs:use miden_node_store::{ConnectionManager, DatabaseError, DatabaseSetupError};
./crates/validator/src/db/mod.rs:pub async fn load(database_filepath: PathBuf) -> Result<miden_node_store::Db, DatabaseSetupError> {
./crates/validator/src/db/mod.rs:    let db = miden_node_store::Db::new(pool);
./crates/validator/src/db/migrations.rs:use miden_node_store::DatabaseError;

[Mirko-von-Leipzig]

@sergerad I think it might be a good idea to first design the crate and the things we want from it?

What I mean by that, is that there are probably things and abstractions we want to add, but if we switch over the store as is immediately then we can't do it piece by piece.

[sergerad]

@Mirko-von-Leipzig I would opt to perform the extraction first and then look to redesign. Should avoid merge conflicts best that way. E.G. with validator and ntx-builder being actively developed w.r.t to db things