* Created venv builders for linux/windows and req flashers + use documentation

* aadd license headers to scripts

* moved scripts, updated paths, changed how reqs are installed, updated linux venv bin path

* update license checker to accomodate for shebangs and batchfile comments

Co-authored-by: Nkezhenxu94 <kezhenxu94@163.com>

- Extract as many commonly-used codes as possible
- Rename the test class to a more general one as contributors tend to copy-paste w/o modifying the class name

Co-authored-by: Nkezhenxu94 <kezhenxu94@163.com>

parameter of urlopen could be either str or `Request`

- Add logging level configuration item
- Add plugin disabling mechanism
- Some trivial chores

- Set operation name `/` when the url is just a domain name
- Rename component `Http` to `General`