[ETHEREUM-CONTRACTS] host should be immutable

[0xdavinchee]

There is no reason the host contract shouldn't be immutable on the SuperAppBaseFlow contract.
Save some gas and also allow SuperApps to be clones/proxies.

[github-actions]

Changelog Reminder

Reminder to update the CHANGELOG.md for any of the modified packages in this PR.

• CHANGELOG.md modified
• Double check before merge

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: +8.81 🎉

Comparison is base (fb7bed2) 87.53% compared to head (95fa7a5) 96.35%.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1542      +/-   ##
==========================================
+ Coverage   87.53%   96.35%   +8.81%     
==========================================
  Files          91       41      -50     
  Lines        4389     2139    -2250     
  Branches      184        0     -184     
==========================================
- Hits         3842     2061    -1781     
+ Misses        503       78     -425     
+ Partials       44        0      -44     

Flag	Coverage Δ
ethereum-contracts	96.35% <0.00%> (ø)
sdk-core	?

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Impacted Files	Coverage Δ
...reum-contracts/contracts/apps/SuperAppBaseFlow.sol	0.00% <0.00%> (ø)

... and 50 files with indirect coverage changes

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[github-actions]

XKCD Comic Relif

Link: https://xkcd.com/1542