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/js2c.py

@@ -57,7 +57,7 @@ def reduce_code(code):
 
 
 def js_to_native_code(path, name, build_type):
-    with open(path, 'r') as js_source:
+    with open(path, 'r', encoding='utf8') as js_source:
         code = js_source.read()
 
     if build_type != 'debug':
@@ -65,13 +65,13 @@ def js_to_native_code(path, name, build_type):
 
     data = format_code(code, 1, 2)
 
-    native_code = """const static char {0}_n[] = "{0}";
-const static char {0}_s[] =
+    native_code = f"""const static char {name}_n[] = "{name}";
+const static char {name}_s[] =
 {{
-{1}
+{data}
 }};
-const static int {0}_l = {2};
-""".format(name, data, len(code))
+const static int {name}_l = {len(code)};
+"""
 
     return native_code
 
@@ -96,13 +96,13 @@ def main():
 
     script_args = parser.parse_args()
 
-    gen_line = "/* This file is generated by %s. Please do not modify. */" % os.path.basename(__file__)
+    gen_line = f"/* This file is generated by {os.path.basename(__file__)}. Please do not modify. */"
 
     gen_output = [LICENSE, "", gen_line, "", HEADER]
     gen_structs = [NATIVE_STRUCT]
 
     if script_args.main:
-        gen_structs.append('  {{ {0}_n, {0}_s, {0}_l }}, \\'.format("main"))
+        gen_structs.append('  { main_n, main_s, main_l }, \\')
 
     files = glob.glob(os.path.join(script_args.js_source_path, '*.js'))
 
@@ -111,14 +111,14 @@ def main():
             name = extract_name(path)
             gen_output.append(js_to_native_code(path, name, script_args.build_type))
             if name != 'main':
-                gen_structs.append('  {{ {0}_n, {0}_s, {0}_l }}, \\'.format(name))
+                gen_structs.append(f'  {{ {name}_n, {name}_s, {name}_l }}, \\')
 
     gen_structs.append('  { NULL, NULL, 0 } \\\n};')
 
     gen_output.append("\n".join(gen_structs))
     gen_output.append(FOOTER)
 
-    with open(os.path.join(script_args.output_path, 'jerry-targetjs.h'), 'w') as gen_file:
+    with open(os.path.join(script_args.output_path, 'jerry-targetjs.h'), 'w', encoding='utf8') as gen_file:
         gen_file.write("\n".join(gen_output))