[compiler] Fix module-level 'use memo' not compiling in annotation mode

[sleitor]

Summary

When compilationMode is set to 'annotation', module-level opt-in directives such as 'use memo' placed at the top of a file were silently ignored. Only function-level directives (inside the function body) triggered compilation, contrary to the documented behavior:

"Place directives at the top of a file to affect all functions in that module."

Root cause

Both getReactFunctionType() and processFn() only inspected the function body's own directives (fn.node.body.directives) when deciding whether to compile in annotation mode. The program-level directives (program.node.directives) were never consulted.

Fix

• Add hasModuleScopeOptIn to ProgramContext (computed once from tryFindDirectiveEnablingMemoization(program.node.directives)).
• In getReactFunctionType(): when compilationMode is 'annotation' and no function-level opt-in is found, fall back to hasModuleScopeOptIn before returning null. This ensures functions in the module are queued for compilation.
• In processFn(): add !programContext.hasModuleScopeOptIn to the annotation-mode skip guard so that the compiled function is actually emitted.
• Add a test fixture use-memo-module-level that verifies 'use memo' at module scope in annotation mode compiles the component.

Behaviour table

Directive	compilationMode	Before	After
function-level 'use memo'	annotation	✅ compiled	✅ compiled
module-level 'use memo'	annotation	❌ not compiled	✅ compiled
no directive	annotation	✅ skipped	✅ skipped
module-level 'use memo'	infer	✅ compiled (infer compiles all)	✅ compiled

Fixes #35868