feat(esp_http_client): Add function to delete all headers set by 'esp_http_client_set_header' (IDFGH-13628)

[DCSBL]

Related to https://esp32.com/viewtopic.php?f=13&t=41695. TL;DR: Headers by persistent sessions created by esp_http_client_init are kept, and it is not easy to remove all headers unless you keep track of which one you set.

This PR adds a function that wraps the already existing http_header_clean function to help with that.

We still mis cleanup functions for other esp_http_client_set_* functions, but lets discuss this idea first :)

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[DCSBL]

Note: I was unable to find unit tests for esp_http_client_delete_header so I did not add a unit test for this new feature.

[nileshkale123]

sha=050ef874eac3c07112a42440e793cf0cfa67aa57

[Alvin1Zhang]

Thanks for contribution again, changes have been merged with 72f3ef8.