message: use CheckpointSnapshot for checkpoints
diff: @@ -486,7 +486,7 @@ export class BriefcaseManager {
  const pathname = this.buildFixedVersionBriefcasePath(iModelId, changeSetId);
  if (!IModelJsFs.existsSync(pathname))
  return;
  - const briefcase = this.initializeBriefcase(requestContext, contextId, iModelId, changeSetId, pathname, openParams, ReservedBriefcaseId.Snapshot);
  + const briefcase = this.initializeBriefcase(requestContext, contextId, iModelId, changeSetId, pathname, openParams, ReservedBriefcaseId.CheckpointSnapshot);
  return briefcase;
  }
  @@ -942,7 +942,7 @@ export class BriefcaseManager {
  private static createFixedVersionBriefcase(requestContext: AuthorizedClientRequestContext, contextId: GuidString, iModelId: GuidString, changeSetId: GuidString, openParams: OpenParams): BriefcaseEntry {
  const pathname = this.buildFixedVersionBriefcasePath(iModelId, changeSetId);
  - const briefcase = new BriefcaseEntry(contextId, iModelId, changeSetId, pathname, OpenParams.fixedVersion(), ReservedBriefcaseId.Snapshot);
  + const briefcase = new BriefcaseEntry(contextId, iModelId, changeSetId, pathname, OpenParams.fixedVersion(), ReservedBriefcaseId.CheckpointSnapshot);
  briefcase.downloadProgress = openParams.downloadProgress;
  briefcase.isPending = this.finishCreateBriefcase(requestContext, briefcase);
  @@ -1015,6 +1015,7 @@ export class BriefcaseManager {
  if (DbResult.BE_SQLITE_OK !== res)
  throw new IModelError(res, "Unable to open Db", Logger.logError, loggerCategory, () => ({ ...briefcase.getDebugInfo(), result: res }));
  + if (nativeDb.getBriefcaseId() !== briefcase.briefcaseId)
  nativeDb.resetBriefcaseId(briefcase.briefcaseId);
  // verify that all following values were set correctly
  