feat(module): generate a module's files in the SDK

[TomChv]

Assemble a module's generated tree here rather than routing through the engine's
built-in TypeScript runtime: bindings from the module-facing schema, the sdk/
directory the runtime mounts as @dagger.io/dagger, the dispatch entrypoint, and
the config files.

The schema is ModuleSource.introspectionSchemaJSON — the same builder call the
engine makes before handing the file to Codegen, so this is the same input, not
an approximation.

The scan runs with the compiler installed beside the introspector rather than in
the module tree: a bare import resolves from the importing file's directory, so
the module's own node_modules is not somewhere the scanner would look.

Exposed as generateModuleLocal and left unwired: Mod.generate still delegates to
the engine while the two are compared. ModConfig.runtime becomes public, since
codegen needs to know which config files a module wants and the detection
already lived there.

Comparing the two outputs turned up three places where our generator — ported
with the client codegen, from an older upstream commit than the engine we pin —
diverged from the engine's:

• Enum members were named with strcase.ToCamel, which mangles consecutive
  capitals: EStarGZ became EstarGz where the engine emits EStarGz. Module code
  written against the engine's bindings would not compile against ours. Upstream
  had already fixed this by routing formatEnum through the same PascalCase rule
  as the rest of the generator; the corrected helper was sitting unused in our
  copy.
• arguments was missing from the JS keyword list, so a field of that name came
  out unescaped instead of as arguments_.
• The entrypoint emitted no source maps. The scan reports a location for every
  declaration and our typedef structs dropped all but the object's on the floor;
  the renderer had no sourceMapExpr at all.

With those fixed, every generated file matches the engine's byte-for-byte for
the same fixture, except core.js — ours is built from the vendored lockfile and
is 1.1MB smaller than the engine's, which builds without one. Verified for the
generate/app fixture by generating it both ways, and for the generate-deps
fixtures by calling a function on the result, which exercises the whole tree,
dependency bindings included, through the engine runtime.

Signed-off-by: Tom Chauveau tom@dagger.io

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