engine: bound this, and promisify / partial as transparent wrappers

[swapnilpaliwal-sd]

• JavaScript: f.bind(o) now gives f's this the value of o (objects and instances, and only for functions no class owns). So this.repo.append() inside a handler bound to { repo } resolves, including when a helper does the handler.bind(context).
• JavaScript: util.promisify(f) now evaluates to whatever f holds. It is recognised from the import of the core util module, so a project's own promisify is unaffected. A field set from promisify(x.m.bind(x)) now resolves to x.m.
• TypeScript: a declared this: T parameter now types this inside the function. The compiler oracle's labels now drop that parameter, as the engine's labels already do.
• Python: a functools.partial(...) call now points to its target wherever the value goes (an attribute, an argument), not only when it is held in a local name.
• Tests: new cases js/73-bound-function-identity and ts/84-declared-this-parameter, and py/08-callables is extended. Each has controls: .call, bind(null), an open fn.bind, an own promisify, this: any, a class member, a partial over a builtin. Both new cases failed before the rules were added.

Checked: JS 89/89, TS 98/98 with oracle, Python 42/42 (torture agree 587, unchanged). On a JS product: probes 46 → 47 with none regressed; edges 0 added, 0 removed, 16 sites re-targeted to a new target, 2 re-tiered.