Fix breaking change in NEW_VULNERABILITY notification JSON format

[nscuro]

Companion change to DependencyTrack/hyades-apiserver#290

Note: Because the original field numbers and types remain untouched, this is not a breaking change schema-wise. The name of the fields has changed, but this is only relevant to the JSON output, which is exactly what we want to fix here.

[nscuro]

buf is failing with:

Error: Field "4" with name "affected_projects_reference" on message "NewVulnerabilitySubject" changed option "json_name" from "affectedProjects" to "affectedProjectsReference".
Error: Field "4" on message "NewVulnerabilitySubject" changed name from "affected_projects" to "affected_projects_reference".

Both findings are expected, given my explanation in the description of this PR.

[nscuro]

I found more occurrences of where the JSON field name generated by Protobuf deviates from what was originally used in vanilla Dependency-Track. Thus, buf is now complaining about these changes, too:

Error: Field "6" with name "sub_title" on message "Vulnerability" changed option "json_name" from "subTitle" to "subtitle".
Error: Field "9" with name "cvss_v2" on message "Vulnerability" changed option "json_name" from "cvssV2" to "cvssv2".
Error: Field "[10](https://github.com/DependencyTrack/hyades/actions/runs/6011875625/job/16306121778?pr=775#step:5:11)" with name "cvss_v3" on message "Vulnerability" changed option "json_name" from "cvssV3" to "cvssv3".
Error: Field "[11](https://github.com/DependencyTrack/hyades/actions/runs/6011875625/job/16306121778?pr=775#step:5:12)" with name "owasp_rr_likelihood" on message "Vulnerability" changed option "json_name" from "owaspRrLikelihood" to "owaspRRLikelihood".
Error: Field "[12](https://github.com/DependencyTrack/hyades/actions/runs/6011875625/job/16306121778?pr=775#step:5:13)" with name "owasp_rr_technical_impact" on message "Vulnerability" changed option "json_name" from "owaspRrTechnicalImpact" to "owaspRRTechnicalImpact".
Error: Field "[13](https://github.com/DependencyTrack/hyades/actions/runs/6011875625/job/16306121778?pr=775#step:5:14)" with name "owasp_rr_business_impact" on message "Vulnerability" changed option "json_name" from "owaspRrBusinessImpact" to "owaspRRBusinessImpact".
Error: Field "1" with name "id" on message "Alias" changed option "json_name" from "id" to "vulnId".

Again, this is expected.

[sonarcloud]

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