feat(support-tickets): add create command to open new tickets

[jean-humann]

Description

Adds ovhcloud support-tickets create, which calls POST /support/tickets/create. The support-tickets subtree already exposes list / get / messages / reply — this completes the CRUD surface for the support API.

Fixes #187.

Example:

ovhcloud support-tickets create \
    --subject 'My issue' \
    --body 'Detailed description' \
    --product publiccloud \
    --category assistance \
    --service-name <id>

Implementation notes

Follows the existing IAM-user-create pattern:

• internal/services/supporttickets/supporttickets.go — CreateSpec struct (one field per request-body property) + TicketCreateExample embed + CreateSupportTicket(cmd, _) that delegates to common.CreateResource with mandatory fields ["body", "subject"]. Output prefers ticketId + ticketNumber from the response, with a nil-value guard so a JSON-null id falls through to a generic success message.
• internal/cmd/supporttickets.go — cobra subcommand exposing typed flags for every field of the request body (--subject, --body, --category, --product, --service-name, --subcategory, --impact, --urgency, --type, --watchers) plus the standard --from-file / --init-file / --editor UX helpers. --from-file and --editor marked mutually exclusive via markFlagsMutuallyExclusive. --type is wired but MarkHidden: the OpenAPI spec marks its values DEPRECATED, but keeping the flag functional means --from-file JSON payloads carrying a type field still parse without an "unknown field" error.
• internal/assets/{assets,assets_wasm}.go — embed support.json, fetched via make schemas UNIVERSE=support.
• internal/services/supporttickets/parameter-samples/ticket-create.json — minimal example body for --init-file / --editor (no serviceName placeholder, so a user who runs --from-file without editing it doesn't POST a literal <your-service-id> string).
• internal/cmd/supporttickets_test.go — happy-path test mirroring the httpmock + tdhttpmock.JSONBody pattern used by TestIAMPolicyCreateCmd, plus two error-path tests: mandatory-field check (mandatory field "subject" is missing) and the --from-file / --editor mutual-exclusion guard.
• doc/ovhcloud_support-tickets*.md — regenerated via make doc.

Type of change

• New feature (non-breaking change which adds functionality)

Checklist:

• My code follows the style guidelines of this project
• I have commented my code
• I ran go mod tidy
• I have added tests that prove my fix is effective or that my feature works

Test plan

• go build ./...
• GOOS=js GOARCH=wasm go build ./...
• go test ./... (includes new TestSupportTicketsCreateCmd + error-path tests)
• make doc — no spurious changes outside the new command
• --help output renders flags grouped correctly (input flags in their own section)
• Manual smoke against eu.api.ovh.com — ticket created end-to-end

DCO

Signed-off-by: Jean Humann <jean.humann@cleyrop.com> on the single commit.

[amstuta]

Thanks for this PR @jean-humann ! I just mentionned a small fix to do in the doc, and after that we're good to merge :)

[amstuta]

Thanks for your contribution @jean-humann !