Add CA bundle version and pinning status to user agent string

[mihir-pradhan]

Description

• Added CA_BUNDLE_VERSION = "1.0" constant in Http.java
• Modified the legacy constructor and ClientBuilder.build() to append ca_bundle/1.0 and (ca_pinning=enabled|disabled) to the user agent string based on the disableCaPinning runtime state
• The pinning status is derived from the same disableCaPinning flag that configures TLS, so the reported value always matches the client's actual pinning state

How Has This Been Tested?

• testDefaultBuilder_includesCaBundleVersion — verifies ca_bundle/1.0 is present in the user agent
• testDefaultBuilder_includesCaPinningEnabled — verifies (ca_pinning=enabled) when pinning is not disabled
• testDisableCaPinning_includesCaPinningDisabled — verifies (ca_pinning=disabled) when disableCaPinning() is called
• testLegacyConstructor_includesCaBundleAndPinningEnabled — verifies both fields present via the deprecated constructor path

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)