[Bugfix] Wasm instantiate process

[yun-yeo]

Summary of changes

Fix to store instantiated contract first before executing response messages, then response messages can utilize instantiated contract.

close #399

Report of required housekeeping

• Github issue OR spec proposal link
• Wrote tests
• Updated API documentation (client/lcd/swagger-ui/swagger.yaml)
• Added a relevant changelog entry: clog add [section] [stanza] [message]

---

(FOR ADMIN) Before merging

• Added appropriate labels to PR
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)
• Confirm added tests are consistent with the intended behavior of changes
• Ensure all tests pass

[codecov]

Codecov Report

Merging #398 into develop will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop     #398   +/-   ##
========================================
  Coverage    66.19%   66.19%           
========================================
  Files          116      116           
  Lines         5887     5887           
========================================
  Hits          3897     3897           
  Misses        1771     1771           
  Partials       219      219           

Impacted Files	Coverage Δ
x/wasm/internal/keeper/contract.go	84.89% <100.00%> (ø)