More explicit config error message

[hu55a1n1]

Closes: #1021

Description

Modifies the configuration file parse error message, so an error that previously looked like so ->

$ hermes start
error: hermes fatal error: parse error: unknown variant `naive`, expected `packets` or `all` for key `global.strategy` at line 62 column 1

LE @adizere -- Now looks like ->

$ hermes start
The Hermes configuration file at path '/Users/adi/.hermes/config.toml' is invalid, reason: parse error: unknown variant `naive`, expected `packets` or `all` for key `global.strategy` at line 49 column 1
Please see the example configuration for detailed information about the supported configuration options: https://github.com/informalsystems/ibc-rs/blob/master/config.toml

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For contributor use:

• Added a changelog entry, using unclog.
• If applicable: Unit tests written, added test to CI.
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Updated relevant documentation (docs/) and code comments.
• Re-reviewed Files changed in the Github PR explorer.

[hu55a1n1]

@adizere and @romac - do you think this fix is sufficient or should we also print the help output in such cases?

[romac]

Can we instead catch the config error and print a more informative message? Maybe something like:

the Hermes configuration file is invalid, reason: etc.
Please see the example configuration for detailed information about the supported configuration options: [link to config.toml]

[hu55a1n1]

Can we instead catch the config error and print a more informative message?

Good point! Done! 👍

[romac]

Thanks! One last thing, can you please update the PR description with the new error message? LGTM otherwise :)

[adizere]

Just had a question, otherwise looks good!

Please consider updating the changelog also (we now use unclog).

[adizere]

Looks great, thanks Shoaib! I did one minor aesthetic change here d17d3e5. Approving and will let you do the merge if you agree with the changes I made.