CLI: Fix help output when provider.name is missing

[medikoo]

When sls --help is run in context of service which does not have set provider.name. The error about property being missing is shown instead of help output.

This patch fixes that

[codecov]

Codecov Report

Merging #9235 (cb534c0) into master (ae67bf4) will decrease coverage by 0.01%.
The diff coverage is 57.14%.

❗ Current head cb534c0 differs from pull request most recent head 9b9bc24. Consider uploading reports for the commit 9b9bc24 to get more accurate results

@@            Coverage Diff             @@
##           master    #9235      +/-   ##
==========================================
- Coverage   86.96%   86.94%   -0.02%     
==========================================
  Files         315      315              
  Lines       11707    11720      +13     
==========================================
+ Hits        10181    10190       +9     
- Misses       1526     1530       +4     

Impacted Files	Coverage Δ
scripts/serverless.js	49.78% <33.33%> (+0.22%)	⬆️
lib/configuration/resolve-provider-name.js	100.00% <100.00%> (ø)

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[pgrzesik]

Looks good 👍