Fix and make smaller browser script

[davidyuk]

before:

$ ls -lah dist 
2.1M aepp-sdk.browser-script.js
6.6M aepp-sdk.browser-script.js.map
328K aepp-sdk.browser.js
1.1M aepp-sdk.browser.js.map
325K aepp-sdk.js
1.1M aepp-sdk.js.map

after this and #1208:

$ ls -lah dist
955K aepp-sdk.browser-script.js
3.5M aepp-sdk.browser-script.js.map
327K aepp-sdk.browser.js
1.1M aepp-sdk.browser.js.map
325K aepp-sdk.js
1.1M aepp-sdk.js.map

fixes aepp-sdk.browser-script.js package, discussed in https://forum.aeternity.com/t/issues-with-sdk8-0-0/9453/8

also should fix this issue: browserify/pbkdf2#48 (comment) 😃

[codecov]

Codecov Report

Merging #1209 (1ce4640) into develop (ef3b505) will decrease coverage by 22.80%.
The diff coverage is n/a.

❗ Current head 1ce4640 differs from pull request most recent head 24f946f. Consider uploading reports for the commit 24f946f to get more accurate results

@@             Coverage Diff              @@
##           develop    #1209       +/-   ##
============================================
- Coverage    93.59%   70.79%   -22.81%     
============================================
  Files           54       54               
  Lines         2609     2609               
  Branches        24       24               
============================================
- Hits          2442     1847      -595     
- Misses         155      759      +604     
+ Partials        12        3        -9     

Impacted Files	Coverage Δ
src/utils/keystore.js	16.00% <0.00%> (-84.00%)	⬇️
src/channel/index.js	7.92% <0.00%> (-81.19%)	⬇️
src/channel/handlers.js	1.66% <0.00%> (-79.17%)	⬇️
src/utils/hd-wallet.js	20.00% <0.00%> (-76.00%)	⬇️
src/channel/internal.js	19.32% <0.00%> (-75.64%)	⬇️
src/utils/bytes.js	43.33% <0.00%> (-56.67%)	⬇️
src/utils/mptree.ts	22.03% <0.00%> (-55.94%)	⬇️
src/utils/string.js	60.00% <0.00%> (-40.00%)	⬇️
src/tx/tx-object.js	58.62% <0.00%> (-36.21%)	⬇️
src/utils/amount-formatter.ts	46.42% <0.00%> (-35.72%)	⬇️
... and 11 more

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[mradkov]

Looks good. Perhaps we can gradually refactor to drop the R usage across the whole SDK?