(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/models/entities/TableRec.ts

@@ -4,7 +4,7 @@ import {ColumnRec, ValidationRec, ViewRec} from 'app/client/models/DocModel';
 import * as modelUtil from 'app/client/models/modelUtil';
 import {MANUALSORT} from 'app/common/gristTypes';
 import * as ko from 'knockout';
-import * as randomcolor from 'randomcolor';
+import randomcolor from 'randomcolor';
 
 // Represents a user-defined table.
 export interface TableRec extends IRowModel<"_grist_Tables"> {

app/client/models/entities/ViewSectionRec.ts

@@ -1,4 +1,4 @@
-import * as BaseView from 'app/client/components/BaseView';
+import BaseView from 'app/client/components/BaseView';
 import {CursorPos} from 'app/client/components/Cursor';
 import {FilterColValues, LinkingState} from 'app/client/components/LinkingState';
 import {KoArray} from 'app/client/lib/koArray';