Improve changelog render for asciidoc

[lcawl]

This PR builds on #3244 (and addresses #3244 (comment)).

It fixes formatting issues that were apparent while testing the docs-builder changelog render command with --format-type asciidoc. For example:

• No list continuation: Multi-block list items (description + Impact + Action) don't use + continuation syntax
• Wrong strong formatting: used Impact: and Action: instead of idiomatic Impact:
• Broken list structure: Additional paragraphs terminate the list item instead of continuing it
• Inconsistent subsections handling: Some renderers ignore the --subsections flag and always add "General::" headers
• Definition lists break list continuation: AsciiDoc definition list syntax (General::) doesn't work with list continuation markers (+)

Screenshots

Before

• Lists with paragraphs and no --subsections aren't aligned well and inject an unexpected "general" area:
  

• Lists with paragraphs and --subsections are smushed together in definition lists
  

After

• Lists with paragraphs and no --subsections work:
  

• Lists with paragraphs and --subsections work by moving away from fragile definition lists:
  

NOTE: Since there are teams who have already said they don't want the descriptions published, I've created #3263 as a follow-on too.

AI Summary

Improves changelog render AsciiDoc output for multi-block list items (description, Impact, Action), aligns Markdown PR/issue link rendering with analyzer-friendly options, fixes AsciiDoc subsection behavior versus --subsections, replaces definition lists with nested sections where grouping is intended, and documents AsciiDoc behavior in the CLI reference.

AsciiDoc

• AsciidocRendererBase
  • Emits list continuation (+) before description text (when continuation applies) and before Impact/Action blocks so bullets stay attached to the list item.
  • Drops two-space indentation of full description blobs; emits the raw description (hidden entries still prefixed with // per line).
  • Uses constrained bold *Impact:* / *Action:* instead of **Impact:** / **Action:**.
• Section / grouping (975b4200)
  • Deprecations, Known Issues, Highlights, Entries-by-area: respect Subsections; when --subsections is off, collapse to a single group without a General-style wrapper.
  • When --subsections is on, replace Component:: definition lists with [float] + ==== Title nested sections (and commented-out equivalents when all entries in the group are hidden).
  • Breaking changes: subtype headers use the same nested-section style instead of bold-only lines; hidden groups get commented // [float] / // ==== ….
• CA1305 / globalization: interpolated section titles use AppendLine(CultureInfo.InvariantCulture, …) where applicable (per second commit diff).

Markdown

• Introduces PrIssueLinkOptions and a single RenderPrIssueLinks(StringBuilder, PrIssueLinkOptions) API (avoids long parameter lists / adjacent booleans).
• Call sites updated in breaking changes, deprecations, known issues, and highlights renderers.

Docs & tests

• docs/cli/changelog/render.md: clarifies that AsciiDoc ignores --dropdowns, and briefly describes list continuation, *Impact:* / *Action:*, and attachment of blocks to list items.
• DropdownRenderTests: AsciiDoc expectations updated for *Impact:* / *Action:*.

Generative AI disclosure

1. Did you use a generative AI (GenAI) tool to assist in creating this contribution?

• Yes
• No

2. If you answered "Yes" to the previous question, please specify the tool(s) and model(s) used (e.g., Google Gemini, OpenAI ChatGPT-4, etc.).

Tool(s) and model(s) used: composer-2, claude-4-sonnet-thinking