Chapel: Consistent kwarg-parsing in mason

[ben-albrecht]

For any mason flags that accept a value (what I'm calling a keyword-arg (kwarg)), we should consistently:

1. support --flag value style
2. support --flag=value style
3. Include the value placeholder in the help output with the format: --flag <value>

Examples include:

mason build --example <example>
mason run --example <example>
mason test --setComm <comm>
mason external find -t <tags>

[ankingcodes]

@ben-albrecht Since I'm already working on a similar issue, I'll be taking this along with #14955

[ben-albrecht]

Thanks @ankingcodes. If possible, it would be best if you were able to separate fixing all mason kwargs (this issue) from adding --moduleName in 2 different PRs.

[ben-albrecht]

Stumbled across https://github.com/chapel-lang/chapel/issues/14990 while testing these out.

[ankingcodes]

@ben-albrecht Got it !

[ankingcodes]

@ben-albrecht can we add mason search --show=packageName to that list ?

[ben-albrecht]

--show is bool flag for mason search still. It requires the search query to return 1 package to work though.

[ankingcodes]

@ben-albrecht We can close this now.
For archival purposes, mason test arg parsing was refactored to select style in this issue.

[ben-albrecht]

Closed by https://github.com/chapel-lang/chapel/pull/16098