Convert the settings store to use the basestore package

[asdine]

• Rename the settings store to settingStore

  sourcegraph/internal/db/settings.go

  Line 17 in a547a87

  type settings struct{}

• Convert the store to use the basestore package so that it can be instantiated without using the global db connection

  sourcegraph/internal/db/basestore/store.go

  Lines 10 to 36 in a547a87

  	// Store is an abstract Postgres-backed data access layer. Instances of this struct
  	// should not be used directly, but should be used compositionally by other stores
  	// that implement logic specific to a domain.
  	//
  	// The following is a minimal example of decorating the base store that preserves
  	// the correct behavior of the underlying base store. Note that `With` and `Transact`
  	// must be re-defined in the outer layer in order to create a useful return value.
  	// Failure to re-define these methods will result in `With` and `Transact` methods that
  	// return a modified base store with no methods from the outer layer. All other methods
  	// of the base store are available on the outer layer without needing to be re-defined.
  	//
  	// type SprocketStore struct {
  	// *basestore.Store
  	// }
  	//
  	// func NewWithHandle(db dbutil.DB) *SprocketStore {
  	// return &SprocketStore{Store: basestore.NewWithHandle(db)}
  	// }
  	//
  	// func (s *SprocketStore) With(other basestore.ShareableStore) *SprocketStore {
  	// return &SprocketStore{Store: s.Store.With(other)}
  	// }
  	//
  	// func (s *SprocketStore) Transact(ctx context.Context) (*SprocketStore, error) {
  	// txBase, err := s.Store.Transact(ctx)
  	// return &SprocketStore{Store: txBase}, nil
  	// }

Example: https://github.com/sourcegraph/sourcegraph/blob/main/internal/db/repos.go#L55-L73

• Make sure the global settings store is usable without initializing it

  sourcegraph/internal/db/repos.go

  Lines 75 to 85 in e612c34

  	// ensureStore instantiates a basestore.Store if necessary, using the dbconn.Global handle.
  	// This function ensures access to dbconn happens after the rest of the code or tests have
  	// initialized it.
  	func (s *RepoStore) ensureStore() {
  	s.mu.Lock()
  	defer s.mu.Unlock()
  	if s.Store == nil {
  	s.Store = basestore.NewWithDB(dbconn.Global, sql.TxOptions{})
  	}
  	}

[github-actions]

Heads up @tsenart - the "team/cloud" label was applied to this issue.