✨ [Browser SDK][RUM-291] Allow logs when cookies are disabled

[mquentin]

What it does

When the cookies are disabled, only the RUM events are blocked. All collected log events will be sent without a session id.

Context
https://datadoghq.atlassian.net/browse/RUMF-291
https://trello.com/c/ttMmQ7vw/70-browser-logs-datadog-browser-agent-doesnt-work-in-an-environment-where-cookies-are-disabled

Client have a native iOS app that opens up a web app in UIWebView that blocks cookies. As a result the DD_LOGS.logger.log does not send anything as neither the session id, neither the 'Tracked or not' mode can be read from the cookies.

Changes

• init process isValidBrowsingContext has now two modes for each package that allow the cookies=OFF for logs and block it for rum
• The mode "Tracked/ not Tracked" is read from the cookies (current behavior) or computed on the fly from the configurations if it is not available (added behavior)
• If the cookies are off, the session id will only be a random id reloaded in every pages. When this case happens, the logs will not pass a session_id to the backend

[bits-bot]

All committers have signed the CLA.

[codecov-io]

Codecov Report

Merging #255 into master will increase coverage by 0.39%.
The diff coverage is 71.42%.

@@            Coverage Diff             @@
##           master     #255      +/-   ##
==========================================
+ Coverage   85.46%   85.86%   +0.39%     
==========================================
  Files          24       24              
  Lines        1321     1323       +2     
  Branches      276      276              
==========================================
+ Hits         1129     1136       +7     
+ Misses        192      187       -5

Impacted Files	Coverage Δ
packages/rum/src/rum.ts	81.92% <0%> (ø)	⬆️
packages/rum/src/rumSession.ts	100% <100%> (ø)	⬆️
packages/rum/src/viewTracker.ts	90.54% <70%> (-3.99%)	⬇️
packages/rum/src/rum.entry.ts	71.42% <0%> (+2.04%)	⬆️
packages/core/src/requestCollection.ts	96.15% <0%> (+13.46%)	⬆️

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[bcaudan]

This PR is actually not a bug fix but a new feature, can you rename your PR to something like:
✨ Allow logs when cookies are disabled