Improve workflow for updating targets

[mattem]

Currently bzlgen expects a file or folder path to generate or update a build target.

tsc_wrapped has a reference to the target being built when it emits diagnostics. In ev, TS2307 is augmented to add additional information to help the developer add deps to ts_library, but no bzlgen command is given, as it's tricky to work backwards from the target to either the file or folder to regenerate the rule.

bzlgen could accept a target as an input, infer the srcs and rule type and run the appropriate generator for updating the target.

Even generating the buildozer command from TS2307 is tricky, as you get a reference to the module specifier, so we'd need to run the same logic as bzlgens ts_lib rule to resolve the import to a label.

Alternatively, expose the resolution API of module specifier to label as a command.