add: mixpanel and posthog

[sirpy]

Description

• added support for mixpanel and posthog
• tested basic integration for web via stories (native not tested)

[johnsmith-gooddollar]

1. Adjusted structure (separate types / apis / provider, export via index)
2. Native wrapper is the same like in GoodDapp, it won't work, reused solution from https://github.com/GoodDollar/GoodDAPP/pull/3886
3. PostHog have RN-only api, added stub for the web, added check does API exists for specific platform

[sirpy]

1. i've asked no refactoring without asking
2. i've asked no refactoring without asking
3. posthog RN works for web as well, that's why i've asked no refactoring without asking

please revert everything

[johnsmith-gooddollar]

@sirpy

Reverted.

What was kept

• export from index (as we're using indexes everywhere)
• had to keep separate types on mix panel to avoid circular dips
• all typings (I replaced a few any's)
• reworked wrapper the most right ways (from the scope of TS) by defining / wrapping each method

[johnsmith-gooddollar]

also

• instead hard-code "APP_OPEN" is now an config option initEvent of PostHog
• added passing sendAutoEvents to init on Mixpanel

[sirpy]

@johnsmith-gooddollar i've reverted please re-review..