add default-new-contest-cmd global config option

Author: Tatamo

src/config.ts

@@ -5,6 +5,7 @@ type Conf = import("conf");
 export const defaults = {
 	["oj-path"]: undefined,
 	["default-contest-dirname-format"]: "{ContestID}",
+	["default-new-contest-cmd"]: undefined,
 	["default-task-dirname-format"]: "{tasklabel}",
 	["default-test-dirname-format"]: "tests",
 	["default-task-choice"]: "inquire",

src/help.ts

@@ -29,6 +29,7 @@ export const format_strings = `Supported format strings:
 export const global_config = `Global config options list:
   oj-path                         install path of online-judge-tools (auto detected)
   default-contest-dirname-format  default name of contest directory (created by \`acc new\` command)
+  default-new-contest-cmd         default --cmd option for \`acc new\` command (see also: \`acc new -h\`)
   default-task-dirname-format     default name of task directory (created by \`acc new|add\` command)
   default-test-dirname-format     default name of sample cases directory
   default-task-choice             default --choice option for \`acc new|add\` command (see also: \`acc new|add -h\`)