Add integration tests.

[dany-pellerin]

The purpose of this PR:

• Adds test to try to prevent accidental breaking changes (requested by FSJ)
• Adding integration tests to the SDK.

Add-ons will be tested in a subsequent PR.

This PR adds 2 dev dependencies:

• jest-localstorage-mock: make it easy to test local storage
• msw: mock edge requests

The sdk.test.js was renamed sdk.test.ts, this is to detect breaking changes, typescript will complain in the test if a property is changed.

The tests are limited to testing the interface and internal behavior of the SDK. It's still possible that changes made in edge would break the SDK.

Coverage report

 PASS  lib/sdk.test.ts
 PASS  lib/addons/gpt.test.js
 PASS  lib/addons/try-identify.test.js
 PASS  lib/addons/topics-api.test.js
 PASS  lib/edge/targeting.test.js
 PASS  lib/core/storage.test.js
 PASS  lib/core/network.test.js
------------------|---------|----------|---------|---------|-------------------
File              | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
------------------|---------|----------|---------|---------|-------------------
All files         |   85.65 |    79.78 |   88.88 |   85.52 |                   
 lib              |     100 |    85.71 |     100 |     100 |                   
  config.ts       |     100 |      100 |     100 |     100 |                   
  sdk.ts          |     100 |    85.71 |     100 |     100 | 103-107,125       
 lib/addons       |   53.03 |    64.51 |   52.63 |   53.03 |                   
  gpt.ts          |   47.36 |     62.5 |      40 |   47.36 | 12,33-44          
  topics-api.ts   |   38.23 |    33.33 |   57.14 |   38.23 | 21-52             
  try-identify.ts |     100 |      100 |     100 |     100 |                   
 lib/core         |    98.3 |    85.71 |     100 |   98.27 |                   
  network.ts      |   95.65 |       70 |     100 |   95.65 | 35                
  storage.ts      |     100 |    94.44 |     100 |     100 | 66                
 lib/edge         |     100 |    92.85 |     100 |     100 |                   
  identify.ts     |     100 |      100 |     100 |     100 |                   
  profile.ts      |     100 |      100 |     100 |     100 |                   
  rtb2.ts         |       0 |        0 |       0 |       0 |                   
  site.ts         |     100 |      100 |     100 |     100 |                   
  targeting.ts    |     100 |    92.85 |     100 |     100 | 36                
  tokenize.ts     |     100 |      100 |     100 |     100 |                   
  uid2_token.ts   |     100 |      100 |     100 |     100 |                   
  witness.ts      |     100 |      100 |     100 |     100 |                   
 lib/test         |     100 |      100 |     100 |     100 |                   
  handlers.ts     |     100 |      100 |     100 |     100 |                   
  mocks.ts        |     100 |      100 |     100 |     100 |                   
  server.ts       |     100 |      100 |     100 |     100 |                   
------------------|---------|----------|---------|---------|-------------------