Add url input and "show aepp" button to wallet-iframe example

[davidyuk]

closes #1883
closes #1886

This PR is supported by the Æternity Crypto Foundation

[codecov]

Codecov Report

Patch coverage: 50.00% and project coverage change: -0.09% ⚠️

Comparison is base (dec62a4) 81.37% compared to head (eb475c8) 81.28%.
Report is 14 commits behind head on develop.

❗ Current head eb475c8 differs from pull request most recent head f6b5bcd. Consider uploading reports for the commit f6b5bcd to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1899      +/-   ##
===========================================
- Coverage    81.37%   81.28%   -0.09%     
===========================================
  Files           94       94              
  Lines         3361     3361              
  Branches       671      671              
===========================================
- Hits          2735     2732       -3     
- Misses         303      305       +2     
- Partials       323      324       +1     

Files Changed	Coverage Δ
src/tx/builder/field-types/fee.ts	95.55% <0.00%> (ø)
src/tx/builder/field-types/gas-price.ts	77.77% <0.00%> (ø)
src/utils/crypto.ts	95.74% <ø> (ø)
src/contract/Contract.ts	75.28% <100.00%> (ø)
src/utils/autorest.ts	90.66% <100.00%> (ø)

... and 1 file with indirect coverage changes

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