Add warning if shell expansion characters make it in to the path

[mcdee]

User hit the situation where they wrapped a shell expansion character for the keymanager options in quotes, so the shell did not expand it. Although we cannot prevent this, we can detect it and highlight it in the logs, as otherwise it is not an obvious mistake and can cause user confusion (especially in situations where we try to help by creating the path directory if it doesn't exist rather than erroring).

This prints a suitable warning in the log on detection of this condition.

Resolves #4998 (as much as we can).

[codecov]

Codecov Report

Merging #5001 into master will increase coverage by 5.5%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #5001      +/-   ##
==========================================
+ Coverage    9.55%   15.05%    +5.5%     
==========================================
  Files         227      102     -125     
  Lines       17913     7676   -10237     
==========================================
- Hits         1712     1156     -556     
+ Misses      15957     6325    -9632     
+ Partials      244      195      -49