feat: posthog integration in new saas flow

[tanmoysrt]

• configure session replay in signup, setup, in-desk billing page
• capture events of product trial request

in session recording, intentionally put that in setTimeout(....) with 3seconds delay. Sometimes posthog doesn't get loaded in browser due to network issue and the page attempt to start recording but as posthog is not loaded, the recording silently failed.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 29.41176% with 12 lines in your changes missing coverage. Please review.

Project coverage is 37.12%. Comparing base (f11ed4a) to head (a645bd2). Report is 34 commits behind head on master.

Files with missing lines	Patch %	Lines
...ype/product_trial_request/product_trial_request.py	29.41%	12 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2147 +/- ## ========================================== - Coverage 37.36% 37.12% -0.24% ========================================== Files 349 355 +6 Lines 29398 29628 +230 ========================================== + Hits 10984 11000 +16 - Misses 18414 18628 +214 ```

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