Support size suffixes in config

[fyrchik]

Fix #857 .

[codecov]

Codecov Report

Merging #893 (19dc15b) into master (6b1e645) will increase coverage by 0.15%.
The diff coverage is 94.11%.

❗ Current head 19dc15b differs from pull request most recent head 2a2bb5d. Consider uploading reports for the commit 2a2bb5d to get more accurate results

@@            Coverage Diff             @@
##           master     #893      +/-   ##
==========================================
+ Coverage   39.16%   39.32%   +0.15%     
==========================================
  Files         244      244              
  Lines       12178    12212      +34     
==========================================
+ Hits         4770     4802      +32     
- Misses       7013     7014       +1     
- Partials      395      396       +1     

Impacted Files	Coverage Δ
cmd/neofs-node/config/cast.go	89.87% <94.11%> (+3.20%)	⬆️

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[fyrchik]

See also spf13/cast#129 .

[532910]

I believe at least terabytes should be supported. BTW, what about floats, like .5Tb for example?

[cthulhu-rider]

@fyrchik pls don't forget to fix linter's remark

[fyrchik]

@532910 floats are not supported, at least for now. I will add TB suffixes.