Allow disabling context-sensitivity for specific functions

[Copilot]

• Add "no-context" value to goblint_context attribute enum in options.schema.json
• Add ana.context.no_fun configuration option to options.schema.json
• Modify mCP.ml's context function to check no-context attribute and ana.context.no_fun option
• Fix crash: return startcontext() instead of [] for no-context functions (returning [] caused assoc n [] to raise Not_found in inner_man's context lookup)
• Update annotating.md documentation
• Add regression tests (attribute, config option, annotation option)

[michael-schwarz]

@copilot: All tests fail, pls fix.

[Copilot]

@copilot: All tests fail, pls fix.

Fixed in fb03adb. The tests were crashing because returning [] from context broke the invariant in inner_man where man.context () |> assoc n would raise Not_found on an empty list for any context-sensitive analysis. The fix returns startcontext() instead — a constant context value shared by all callers of the no-context function, achieving context-insensitivity while keeping valid context entries for all analyses.

[michael-schwarz]

@copilot tests still fail.