Implement the rest of the ABI

[avidal]

https://docs.rs/fastly-sys/0.3.3/fastly_sys/index.html

• [x] xqd_body_append
• [ ] xqd_body_close_downstream
• [x] xqd_body_new
• [x] xqd_body_read
• [x] xqd_body_write
• [x] xqd_log_endpoint_get
• [x] xqd_log_write
• [ ] xqd_pending_req_poll
• [ ] xqd_pending_req_select
• [ ] xqd_pending_req_wait
• [x] xqd_req_body_downstream_get
• [x] xqd_req_cache_override_set
• [x] xqd_req_downstream_client_ip_addr
• [ ] xqd_req_downstream_tls_cipher_openssl_name
• [ ] xqd_req_downstream_tls_client_hello
• [ ] xqd_req_downstream_tls_protocol
• [ ] xqd_req_header_append
• [ ] xqd_req_header_insert
• [x] xqd_req_header_names_get
• [x] xqd_req_header_remove
• [x] xqd_req_header_values_get
• [x] xqd_req_header_values_set
• [x] xqd_req_method_get
• [x] xqd_req_method_set
• [x] xqd_req_new
• [ ] xqd_req_original_header_count
• [x] xqd_req_original_header_names_get
• [x] xqd_req_send
• [ ] xqd_req_send_async
• [x] xqd_req_uri_get
• [x] xqd_req_uri_set
• [x] xqd_req_version_get
• [x] xqd_req_version_set
• [ ] xqd_resp_header_append
• [ ] xqd_resp_header_insert
• [x] xqd_resp_header_names_get
• [x] xqd_resp_header_remove
• [ ] xqd_resp_header_value_get
• [x] xqd_resp_header_values_get
• [x] xqd_resp_header_values_set
• [x] xqd_resp_new
• [x] xqd_resp_send_downstream
• [x] xqd_resp_status_get
• [x] xqd_resp_status_set
• [x] xqd_resp_version_get
• [x] xqd_resp_version_set

[themightychris]

Finished an initial bootstrap-ification of the form in #220 :

[mariekers]

GORGEOUS

[mariekers]

One more question:
I am interested in volunteering: <1 hour/week, 1-2 hours/week, 3-4 hours/week, 5+ hours/week