cli: add missing env vars to --help

This adds NODE_TLS_REJECT_UNAUTHORIZED, SSL_CERT_DIR,
SSL_CERT_FILE, and UV_THREADPOOL_SIZE to the --help menu.

PR-URL: #24383
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Ouyang Yadong <oyydoibh@gmail.com>
Reviewed-By: Weijia Wang <starkwang@126.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

lib/internal/print_help.js

@@ -29,9 +29,17 @@ const envVars = new Map([
     'of stderr' }],
   ['NODE_REPL_HISTORY', { helpText: 'path to the persistent REPL ' +
     'history file' }],
+  ['NODE_TLS_REJECT_UNAUTHORIZED', { helpText: 'set to 0 to disable TLS ' +
+    'certificate validation' }],
   ['NODE_V8_COVERAGE', { helpText: 'directory to output v8 coverage JSON ' +
     'to' }],
-  ['OPENSSL_CONF', { helpText: 'load OpenSSL configuration from file' }]
+  ['OPENSSL_CONF', { helpText: 'load OpenSSL configuration from file' }],
+  ['SSL_CERT_DIR', { helpText: 'sets OpenSSL\'s directory of trusted ' +
+    'certificates when used in conjunction with --use-openssl-ca' }],
+  ['SSL_CERT_FILE', { helpText: 'sets OpenSSL\'s trusted certificate file ' +
+    'when used in conjunction with --use-openssl-ca' }],
+  ['UV_THREADPOOL_SIZE', { helpText: 'sets the number of threads used in ' +
+    'libuv\'s threadpool' }]
 ].concat(hasIntl ? [
   ['NODE_ICU_DATA', { helpText: 'data path for ICU (Intl object) data' +
     hasSmallICU ? '' : ' (will extend linked-in data)' }]