chore: replace deprecated functions

[zemyblue]

Description

Replace deprecated functions since go 1.16 or 1.17.

• ioutil.ReadFile -> os.ReadFile
• ioutil.ReadAll -> io.ReadAll
• ioutil.TempDir -> os.MkdirTemp
• ioutil.WriteFile -> os.WriteFile
• ioutil.NopCloser -> io.NopCloser
• ioutil.Discard -> io.Discard
• ioutil.TempFile -> os.CreateTemp
• ioutil.Discard -> io.Discard
• ioutil.ReadDir -> os.ReadDir

Motivation and context

The io/ioutil has been deprecated since Go 1.16.

How has this been tested?

Screenshots (if appropriate):

Checklist:

• I followed the contributing guidelines and code of conduct.
• I have added a relevant changelog to CHANGELOG.md
• I have added tests to cover my changes.
• I have updated the documentation accordingly.
• I have updated API documentation client/docs/swagger-ui/swagger.yaml

[codecov]

Codecov Report

Merging #694 (6b7951e) into main (551bc1c) will decrease coverage by 0.01%.
The diff coverage is 64.15%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #694      +/-   ##
==========================================
- Coverage   61.15%   61.14%   -0.02%     
==========================================
  Files         873      873              
  Lines       98421    98432      +11     
==========================================
- Hits        60192    60182      -10     
- Misses      34644    34670      +26     
+ Partials     3585     3580       -5     

Impacted Files	Coverage Δ
crypto/keyring/keyring.go	59.55% <0.00%> (ø)
simapp/state.go	0.00% <0.00%> (ø)
simapp/utils.go	21.62% <0.00%> (ø)
testutil/rest.go	0.00% <0.00%> (ø)
x/auth/client/cli/tx_multisign.go	0.00% <0.00%> (ø)
x/genutil/client/cli/gentx.go	0.00% <0.00%> (ø)
x/params/client/utils/utils.go	47.61% <0.00%> (ø)
x/simulation/event_stats.go	0.00% <0.00%> (ø)
x/wasm/client/cli/query.go	0.00% <0.00%> (ø)
types/rest/rest.go	76.01% <33.33%> (ø)
... and 21 more