[Scripts][GUI] Overhaul translation ingestion script and update translations from Transifex

[Fuzzbawls]

Our update-translations.py was in dire need of updating since Transifex depreciated their old tx CLI utility in favor of their new CLI utility (of the same name). Minor changes to the .tx/config file format were needed to be compliant, and the translation ingestion script itself (update-translations.py) was updated to be more in-line with upstream's version, with some additional Flake8/PEP compliance rules being adhered to.

The first commit is really the only commit that needs actual code review. The second commit is automatically generated changes resulting from running the update-translations.py script, with ONE caveat: I changed the minimum translation threshold from 80% to 50% solely for the purpose of not loosing any already translated languages.

I felt this necessary for the master branch (which will never be used for final release translations) simply to showcase that translating the core wallet is an ongoing process that is never truly "finished", as strings change or new strings get introduced between wallet release versions.

It also gives users of otherwise incomplete translated languages a chance to view how their language translations appear in a compiled GUI wallet, and provide feedback if there are any clipping issues.

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This PR does introduce two completely new wallet translations never before seen with PIVX:

• Bengali (bn) (95.68% translated)
• Persian (fa) (95.68% translated)

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And now for the part where we need some more help prior to the final 6.0 release;

The following languages are in jeopardy of being EXCLUDED from the final 6.0 release unless they can reach a minimum of 80% translated strings. Listed in descending order based on completion percentage:

• Polish (pl) (79.59%)
• Spanish (es) (79.02%)
• Spanish (Spain) (es_ES) (79.02%)
• Dutch (nl) (77.75%)
• Italian (it) (76.19%)
• Russian (ru) (75.9%)
• Chinese (China) (zh_CN) 67.26%
• Chinese (Taiwan) (zh_TW) 67.26%
• Turkish (tr) 59.32%
• Swedish (sv) 52.16%

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Any translator that has contributed translations via Transifex for the PIVX Core wallet is highly encouraged to check-in on the Transifex website, as no language (other than the English source) is 100% complete at the time of writing this PR.

Anyone not already part of the PIVX translation effort on Transifex that would like to join the effort, you can goto https://explore.transifex.com/pivx-project/ and request to join the PIVX Core Wallet project.*

*Note: the completion percentages represented on the public page are TOTAL over all resource versions available (we keep many historical resource versions for archival purposes), and NOT indicative of the specific targeted resource version percentages listed above

[panleone]

tACK b0d6e37
tested that the scripts works, pivx-qt is translated and the git diff is consistent with the second commit (with the threshold locally changed to 50%)

[Liquid369]

tACK b0d6e37