update to_money to have the same behaviour as Money.new

[elfassy]

Why

To avoid gotchas, string.to_money("USD") should behave exactly the same as Money.new(string, "USD")
Also adding a deprecation warning to help us search the logs and identify incorrect uses for codebases with the legacy_deprecation option

# before
"1.234".to_money == Money.new("1234") # the . is assumed to be a european thousand separator
"1,234".to_money == Money.new("1234") # the , is assumed to be a NA thousand separator

# after
"1.234".to_money == Money.new("1.234") # the . is assumed to be a decimal delimiter
"1,234".to_money == Money.new("1,234") #=> raise exception 

What

Make the change but keep the old behaviour under the legacy_deprecations option... until we're confident we can remove it. For those with that legacy support, they can rely on the newly added rubocop rule to help them migrate away from the old .to_money

[elfassy]

note to self: also reactivate logs for these deprecations https://github.com/Shopify/shopify/commit/7cbada73b5dea61eb87794da0be0a3ab0b7bbb44

PR: https://github.com/Shopify/shopify/pull/433911

[csalvato]

This means that the gem consumer will need to set legacy_deprecations to true for this to maintain the old behavior, correct?

[elfassy]

yes, correct, and that should only be used in core