(core) Removing NEW_DEAL flag

Summary:
Removing NEW_DEAL flag checks and exposing all new deal features as default.
Also removing Pages.ts as it was moved to grist-core.

Test Plan: Existing and updated tests.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D3572

app/server/lib/sendAppPage.ts

@@ -55,7 +55,6 @@ export function makeGristConfig(homeUrl: string|null, extra: Partial<GristLoadCo
     survey: Boolean(process.env.DOC_ID_NEW_USER_INFO),
     tagManagerId: process.env.GOOGLE_TAG_MANAGER_ID,
     activation: (mreq as RequestWithLogin|undefined)?.activation,
-    newDeal: process.env.NEW_DEAL === 'true',
     ...extra,
   };
 }