Make ContractAddrLen variable

[chipshort]

This should allow chains to customize the address length for contract addresses (both classic and instantiate2).
It's related to this issue: CosmWasm/cosmwasm#2155 (comment)
Injective implemented this for their fork (they use 20).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 46.22%. Comparing base (4c5feae) to head (b856840).
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2111      +/-   ##
==========================================
+ Coverage   46.20%   46.22%   +0.01%     
==========================================
  Files          78       78              
  Lines       10810    10810              
==========================================
+ Hits         4995     4997       +2     
+ Misses       5368     5367       -1     
+ Partials      447      446       -1     

Files with missing lines	Coverage Δ
x/wasm/types/types.go	60.25% <ø> (ø)

... and 1 file with indirect coverage changes

[pinosu]

LGTM 👍