Consider removing support for Finance::Quote

1. There are several open APIs available that provide quotes and has been doing it for many years now. This wasn't the case when Finance::Quote was popular, and obtaining quotes required scraping website's html. It's a personal opinion, but I consider Finance::Quote redundant by now.
2. Newbie users get confused by its presence in the Security Wizard right next to Online Source drop-down list selector:
3. It requires manual installation of a Perl distribution + cpan module on macOS platform ([1]) and on Windows, since we don't ship it with the binary package. I don't think any of the popular Linux distributions add it as a default dependency, either.
4. It was reported it doesn't work properly (macOS, linux – this one is most likely due to a missing perl module)
5. Adds complexity to the codebase
6. Its development has mostly stalled, the maintainers don't respond to patch sign-off requests. From my anecdotal evidence, I tried to add support for Warsaw Stock Exchange quotes a few years back and never got a response.
7. While it provides many backends, I have personally tried to use a few (mainly Fidelity) that didn't work at all, because they were written to scrape the prices from old versions of the websites, when the prices weren't published via APIs.
8. Our built-in quotes support provides support for price only. Finance::Quote can provide many more values than just price, yet we ignore them and parse price only anyway:

void WebPriceQuote::slotParseQuote(const QString& _quotedata)
{
(...)
  QRegularExpression webIDRegExp(d->m_source.m_webID);
  QRegularExpression dateRegExp(d->m_source.m_date);
  QRegularExpression priceRegExp(d->m_source.m_price);
(...)

9. Interestingly, even our manual says that

Future currency rate updates will not use Finance::Quote, and will always use the native retrieval method

[1] while macOS ships with Perl, Apple warns against installing own cpan modules or otherwise modifying it. For that reason, sane developers will use a separate perl distribution provided e.g. by HomeBrew. Moreover, macOS 10.15 no longer ships any of the 3rd party frameworks (python, perl, ruby) it previously provided.