(core) Faster builds all around.

Summary:
Building:
- Builds no longer wait for tsc for either client, server, or test targets. All use esbuild which is very fast.
- Build still runs tsc, but only to report errors. This may be turned off with `SKIP_TSC=1` env var.
- Grist-core continues to build using tsc.
- Esbuild requires ES6 module semantics. Typescript's esModuleInterop is turned
  on, so that tsc accepts and enforces correct usage.
- Client-side code is watched and bundled by webpack as before (using esbuild-loader)

Code changes:
- Imports must now follow ES6 semantics: `import * as X from ...` produces a
  module object; to import functions or class instances, use `import X from ...`.
- Everything is now built with isolatedModules flag. Some exports were updated for it.

Packages:
- Upgraded browserify dependency, and related packages (used for the distribution-building step).
- Building the distribution now uses esbuild's minification. babel-minify is no longer used.

Test Plan: Should have no behavior changes, existing tests should pass, and docker image should build too.

Reviewers: georgegevoian

Reviewed By: georgegevoian

Subscribers: alexmojaki

Differential Revision: https://phab.getgrist.com/D3506

app/client/components/ChartView.ts

@@ -1,4 +1,4 @@
-import * as BaseView from 'app/client/components/BaseView';
+import BaseView from 'app/client/components/BaseView';
 import {GristDoc} from 'app/client/components/GristDoc';
 import {consolidateValues, formatPercent, sortByXValues, splitValuesByIndex,
         uniqXValues} from 'app/client/lib/chartUtil';
@@ -6,7 +6,7 @@ import {Delay} from 'app/client/lib/Delay';
 import {Disposable} from 'app/client/lib/dispose';
 import {fromKoSave} from 'app/client/lib/fromKoSave';
 import {loadPlotly, PlotlyType} from 'app/client/lib/imports';
-import * as DataTableModel from 'app/client/models/DataTableModel';
+import DataTableModel from 'app/client/models/DataTableModel';
 import {ColumnRec, ViewFieldRec, ViewSectionRec} from 'app/client/models/DocModel';
 import {reportError} from 'app/client/models/errors';
 import {KoSaveableObservable, ObjObservable, setSaveValue} from 'app/client/models/modelUtil';