Remove WIF and NEP2 support in --wallet argument

[acid-ant]

Closes: #1128

[codecov]

Codecov Report

Merging #1789 (4198ef2) into master (3df98ce) will decrease coverage by 0.06%.
The diff coverage is 100.00%.

❗ Current head 4198ef2 differs from pull request most recent head 918a12f. Consider uploading reports for the commit 918a12f to get more accurate results

@@            Coverage Diff             @@
##           master    #1789      +/-   ##
==========================================
- Coverage   33.48%   33.41%   -0.07%     
==========================================
  Files         353      352       -1     
  Lines       23982    23962      -20     
==========================================
- Hits         8030     8008      -22     
- Misses      15286    15287       +1     
- Partials      666      667       +1     

Impacted Files	Coverage Δ
cmd/neofs-cli/internal/key/wallet.go	87.50% <ø> (-6.25%)	⬇️
cmd/neofs-cli/internal/key/raw.go	62.96% <100.00%> (-10.02%)	⬇️

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[carpawell]

1. Could you, please, add a commit sign-off? We have a CI step that has failed in that PR.
2. We also should fix the flag description. E.g. neofs-cli container create -h: -w, --wallet string WIF (NEP-2) string or path to the wallet or binary key
3. It is common practice to write commit msg imperatively: Removed -> Remove.

[realloc]

Please avoid merge commits at rebase at all cost.

[carpawell]

@acid-ant, for future: we also try to keep CHANGELOG.md in an actual state after every PR.

[realloc]

Is there a related issue? If not, could you please take care of labels and projects?

[acid-ant]

Is there a related issue? If not, could you please take care of labels and projects?

This is a related issue #1128

[acid-ant]

@acid-ant, for future: we also try to keep CHANGELOG.md in an actual state after every PR.

Updated. Please review.