Modernize python and update pylint (#5096)

Update code to conform to the newer version of pylint available in
ubuntu-22.04, with few exceptions:
    - disabled `import-outside-toplevel` for `main()` in
      `jerry_client.py`
    - disabled `consider-using-with` for the logfile of `TestSuite` in
      `test262-harness.py` as using `with` is not practical in that case

Update test262-harness.py to use argparse instead of the now deprecated
optparse

Rename variables in jerry_client_main.py that redefined python builtins
or shadowed variables from an outer scope

Update python files to use f-stirngs

Add minimum python versions (3.6 and 3.8) to the CI jobs: without it the
default python version did not support the `with` statement for
`subprocess.Popen` used in `build.py` on macos, or in some cases f-stirngs

Remove `from __future__` imports that are no-ops in python 3

Remove shebang from non executable files

Re-enable most pylint checkers, except `missing-docstring`

JerryScript-DCO-1.0-Signed-off-by: Máté Tokodi mate.tokodi@szteszoftver.hu

tools/gen_c_source.py

@@ -33,11 +33,11 @@ def format_code(code, indent, digit_number=4):
     def regroup(list_to_group, num):
         return [list_to_group[i:i+num] for i in range(0, len(list_to_group), num)]
 
-    def hex_format(char, digit_number):
+    def hex_format(char, padding):
         if isinstance(char, str):
             char = ord(char)
 
-        return ("0x{:0%sx}" % digit_number).format(char)
+        return f"{char:#0{padding + 2}x}"
 
     lines = []