Reject configuration with unknown fields

[End-rey]

Closes #2663, #1950.

The problems I have encountered:

• node config: grpc section with list of structures and node section with unlimited number of attributes.
• .env files are not being processed, because of the work of the viper package. Should I do it? It might be more difficult.

[codecov]

Codecov Report

Attention: Patch coverage is 86.11111% with 15 lines in your changes missing coverage. Please review.

Project coverage is 23.12%. Comparing base (838126c) to head (652e230).
Report is 14 commits behind head on master.

Files with missing lines	Patch %	Lines
cmd/neofs-ir/defaults.go	0.00%	7 Missing ⚠️
cmd/internal/configvalidator/validate.go	91.54%	4 Missing and 2 partials ⚠️
cmd/neofs-node/config/config.go	50.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2981      +/-   ##
==========================================
+ Coverage   22.88%   23.12%   +0.23%     
==========================================
  Files         785      788       +3     
  Lines       58806    58912     +106     
==========================================
+ Hits        13457    13622     +165     
+ Misses      44469    44407      -62     
- Partials      880      883       +3     

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[End-rey]

There was a problem that the default value of the list was a slice with a length of 0, so I added a check for this. And now my devenv works.
But it seems like automated system tests didn't pass because the ir or node didn't run well. How can I find out what the error was that caused them to fail? Maybe there is a bad configuration?

[roman-khimov]

Can this be solved with https://pkg.go.dev/github.com/spf13/viper#UnmarshalExact?

[End-rey]

Can this be solved with https://pkg.go.dev/github.com/spf13/viper#UnmarshalExact?

Partially it can, but there are such fields in the config, for example, node.attribute_* and there can be as many as you like, so the tag ,remain is used, because of which any incorrect fields will fall into this field and then validation will be successful, although in fact there will be an error. I tried this method and it didn't pass my tests.