Add an option to disable CA certificate pinning

[cisco-dmytro-hissa]

Description

1. Client::disableCaPinning() — Fluent method that sets disable_ca_pinning option. Mutually exclusive with custom CA certs (setRequesterOption("ca", ...)) — throws InvalidArgumentException if both are used.
2. CurlRequester::options() — When disable_ca_pinning is true, skips setting CURLOPT_CAINFO entirely, relying on the system's default CA store. TLS verification (CURLOPT_SSL_VERIFYPEER + CURLOPT_SSL_VERIFYHOST)
   remains mandatory.
3. FileRequester::options() — When disable_ca_pinning is true, skips setting cafile in the SSL stream context, using the system's default trust store.

How Has This Been Tested?

• testDisableCaPinning — verifies fluent interface and option is set
• testDisableCaPinningWithCustomCaThrows — mutual exclusion (CA set first)
• testSetCustomCaWithDisabledPinningThrows — mutual exclusion (pinning disabled first)
• testDisableCaPinningSetsOption — verifies the option is passed to the requester
• CurlRequesterTest — 5 tests verifying the curl option logic (default CA, disabled pinning removes CAINFO, SSL verify stays on, custom CA, IGNORE mode)

Types of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)