http_server: api: v1: backport fix for CVE-2024-4323

* api/v1/traces: validate inputs when enabling traces.

validate the array of inputs when enabling multiple traces that
they are strings.

this patch also refactors out the allocation of said input name.

* api/v1/traces: disable traces api when tracing is disabled.

* api/v1/trace: use macros for strings and lengths in responses.

avoid strlen when creating http response, especially in loops,
by predefining them via macros.

* api/v1/trace: use sizeof for string length macros.

* api/v1/trace: use signed lenghts for strings.

this avoid potential integer overflows when using them as
specifiers for format strings.

* api/v1/traces: use macro for inputs string.

* api/v1/traces: use sizeof when comparing against base path.

* api/v1/traces: replace strlen with flb_sds_len when using flb_sds_t.

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Signed-off-by: Phillip Adair Stewart Whelan <phillip.whelan@chronosphere.io>
Signed-off-by: Phillip Whelan <phil@calyptia.com>
Co-authored-by: Phillip Whelan <phil@calyptia.com>