[REF-3016]Allow special characters in upload ID

[ElijahAhianyo]

We should allow special characters as upload id for the following:

rx.upload(..., id=<upload_id>),
rx.selected_files(<upload_id>)
rx.upload_files(upload_id=<upload_id>)
rx.clear_selected_files(<upload_id>)

fixes #3444

[linear]

REF-3016 Upload ID must not contain - or other "special" characters

[masenf]

i think we still have a problem when the id contains the backtick character...

>>> import reflex.components.core.upload as upl
>>> print(str(upl.upload_file("foo`bar")))
{e => setFilesById(filesById => {
    const updatedFilesById = Object.assign({}, filesById);
    updatedFilesById[`foo`bar`] = e;
    return updatedFilesById;
  })
    }

If we convert the id_ to a Var with _var_is_string=True, and then get the _var_name_unwrapped, then it provides the outer backticks automatically and escapes the inner backtick(s)

>>> import reflex as rx
>>> rx.Var.create_safe("foo`bar", _var_is_string=True)._var_name_unwrapped
'`foo\\`bar`'