* feat(upload): target can be a function to get target URL

* feat(upload): checkSuccess support cb

* fix(upload): checkSuccess add the second param file

* test(upload): target and checkSuccess test

* docs(upload): target[function] and checkSuccess async docs

* feat(upload): headers and data support function too

* docs(upload): add headers & data function doc

* feat(upload): upload component add multiple & accept prop

* docs(upload): add multiple & accept doc