Render order-sensitive ini config files from an ordered list

[khusmann]

Part 1 of 2 for #944.

rstudio-library's ini helpers render a config file from a map, and Go templates iterate maps in sorted key order. For files whose behavior depends on the order of their sections or entries — /etc/rstudio/profiles, launcher.*.profiles.conf, launcher.*.resources.conf, repos.conf — that silently changes what the file does, and nothing in values.yaml shows it.

This PR adds the order-preserving form to the library. Part 2 bumps rstudio-workbench onto it, adds the deprecation warning for the map form, and updates the docs — it has to wait until rstudio-library 0.1.38 is published, since consumers resolve the library from helm.rstudio.com rather than the working tree.

Changes

A file's contents may now be a list, and it renders in the order written:

config:
  server:
    profiles:
      - "*":
          max-memory-mb: 1024
      - "@analysts":
          max-memory-mb: 4096
  session:
    repos.conf:
      - Internal: https://pkgs.example.com/internal
      - CRAN: https://packagemanager.posit.co/cran/latest

Each list item is a map, rendered as one of:

Item shape	Renders as
one key, map value	a [name] section with its key=value lines
one key, scalar value	a single name=value line
two or more keys	key=value lines followed by a blank line (a record)

• rstudio-library.config.ini (_config.tpl) accepts the list form anywhere it renders a file, via a new rstudio-library.config.ini.entry helper. Previously a list of single-entry maps rendered broken lines like *=map[max-memory-mb:1024], with no section headers at all.
• rstudio-library.profiles.ini.advanced, .singleFile, and .json-from-overrides-config (_profiles.tpl) accept the same list form for a profiles file's sections, including the job-json-overrides merging. When an ordered list omits a [*] section, the chart-supplied job-json-overrides defaults are prepended as one, matching what the map form produced.
• New rstudio-library.config.entries helper normalizes either form into an ordered list of entries.

Compatibility

The multi-key record shape is deliberate: config.session.r-versions already uses a list, and /etc/rstudio/r-versions separates R entries by blank lines. Keying on item arity — the "list of one-entry maps" from #944 — lets both forms coexist.

Verified byte-identical output: rendering every values file under charts/rstudio-workbench/{lint,ci}/ and charts/rstudio-connect/{lint,ci}/ before and after this change produces identical manifests.

One behavior change: a list item with exactly one key and a scalar value no longer emits a trailing blank line, since it is now an ordered entry rather than a one-field record. This only affects a single-field r-versions record (e.g. a lone - Path: /opt/R/4.0.2); two-or-more-field records are unchanged.

Testing

other-charts/rstudio-library-test covers, for both config.ini and the profiles helpers:

• the list form for each order-sensitive file — sections and entries render in order, with headers where the file has them
• the map form — renders sorted by name, as it does today
• the raw string form — still verbatim
• multi-field list items — still blank-line separated records
• repeated section names (launcher.conf's cluster: list) — unchanged
• a non-map list item — fails with a clear message

Ran the CI test loop (helm dependency update + helm unittest per chart) against a clean worktree: 452 tests pass across all 5 charts, with the other product charts still on their published library pins. check-uncommitted-changes.sh and check-news-entries.sh both pass.