CBOM 1.7: protocolProperties JSON schema and XSD diverge (relatedCryptographicAssets, cryptoRefArray, tlsGroups, tlsSignatureSchemes)

## Summary

In CycloneDX 1.7, the JSON schema and the XSD disagree on the content model of
`cryptoProperties.protocolProperties`. A CBOM that is valid against the official JSON
schema cannot be serialized to XML that validates against the official XSD, and vice
versa.

## Details

JSON schema (`bom-1.7.schema.json`, `definitions.cryptoProperties.properties.protocolProperties.properties`)
lists:

```
type, version, cipherSuites, cryptoRefArray, ikev2TransformTypes, relatedCryptographicAssets
```

XSD (`bom-1.7.xsd`, the `protocolProperties` element's complexType sequence) lists:

```
type, version, cipherSuites, algorithms, identifiers, tlsGroups,
tlsSignatureSchemes, ikev2TransformTypes, cryptoRef
```

Concretely:

1. **`relatedCryptographicAssets` is JSON-only.** It is present in the JSON schema for
`protocolProperties` but has no counterpart element in the XSD. The sibling
properties `certificateProperties` and `relatedCryptoMaterialProperties` *do* have
`relatedCryptographicAssets` in both serializations (XSD elements at the
`certificateProperties` and `relatedCryptoMaterialProperties` complexTypes), which
suggests the omission under `protocolProperties` is an oversight rather than a
deliberate serialization difference.
-- see https://github.com/CycloneDX/specification/issues/1018
2. **`tlsGroups` and `tlsSignatureSchemes` are XSD-only.** They have no JSON-schema
counterpart under `protocolProperties` (the JSON schema has no TLS parameter
object at all beyond `cipherSuites`).
3. **`cryptoRefArray` (JSON) vs `cryptoRef` (XSD) and `algorithms`/`identifiers`
(XSD-only)** — these may be intentional JSON↔XML representation differences, but
it would be useful to confirm and document the intended mapping.

## Impact

Any JSON→XML (or XML→JSON) conversion of a 1.7 CBOM that uses
`protocolProperties.relatedCryptographicAssets` (or the XSD-only TLS fields) cannot
produce output that validates against the other serialization's official schema.
Tooling must either emit schema-invalid documents or silently drop conformant data.

## Environment

- Schemas fetched from the `CycloneDX/specification` repository (master, `schema/`
directory), also published at `https://cyclonedx.org/schema/bom-1.7.schema.json`
and `bom-1.7.xsd`.
- Observed while implementing bidirectional JSON↔XML conversion for CycloneDX 1.7
in an SBOM conversion tool.

## Suggested fix

Align the two serializations for `protocolProperties`: add `relatedCryptographicAssets`
to the XSD (mirroring `certificateProperties`/`relatedCryptoMaterialProperties`), and
either add `tlsGroups`/`tlsSignatureSchemes` to the JSON schema or remove them from
the XSD. A documented JSON↔XML field mapping for `cryptoRefArray`/`cryptoRef` and
`algorithms`/`identifiers` would also help implementers.