code: language cleanup in comments

Based on the standards and guidelines we use for our documentation.

 - expand contractions (they're => they are etc)
 - host name = > hostname
 - file name => filename
 - user name = username
 - man page => manpage
 - run-time => runtime
 - set-up => setup
 - back-end => backend
 - a HTTP => an HTTP
 - Two spaces after a period => one space after period

Closes #14073

.github/scripts/badwords.txt

@@ -53,6 +53,7 @@ file name\b:filename
 file names\b:filenames
 \buser name\b:username
 \buser names\b:usernames
+\bpass phrase:passphrase
 didn't:did not
 doesn't:does not
 won't:will not