Use conditional hooks for money precision

Move the `Money.default_infinite_precision` test setup from a shared
context into global, conditional RSpec hooks.

The previous `shared_context` approach, which relied on implicit
metadata inclusion, is deprecated and was failing with the modern
`shared_context_metadata_behavior = :apply_to_host_groups` setting.

An explicit `include_context` is unsuitable because this behavior is
sometimes required for individual examples (`it` blocks), where
contexts cannot be included.

This commit defines global `before` and `after` hooks in the RSpec
configuration that are filtered by the
`:default_infinite_precision_true` metadata tag. This provides a
declarative and efficient way to apply the necessary setup and teardown
to any example group or individual example without repetitive code,
while aligning with modern RSpec practices.

Close #1136

Author: tagliala

spec/spec_helper.rb

@@ -62,8 +62,7 @@
   # compatibility in RSpec 3). It causes shared context metadata to be
   # inherited by the metadata hash of host groups and examples, rather than
   # triggering implicit auto-inclusion in groups with matching metadata.
-  # TODO: enable this option. Tracked in RubyMoney/money#1136
-  # config.shared_context_metadata_behavior = :apply_to_host_groups
+  config.shared_context_metadata_behavior = :apply_to_host_groups
 
   # This allows you to limit a spec run to individual examples or groups
   # you care about by tagging them with `:focus` metadata. When nothing
@@ -116,22 +115,20 @@
   config.before(:each) do
     Money.default_currency = Money::Currency.new("USD")
   end
-end
-
-def reset_i18n
-  I18n.backend = I18n::Backend::Simple.new
-end
 
-RSpec.shared_context "with infinite precision", :default_infinite_precision_true do
-  before do
+  config.before(:each, :default_infinite_precision_true) do
     Money.default_infinite_precision = true
   end
 
-  after do
+  config.after(:each, :default_infinite_precision_true) do
     Money.default_infinite_precision = false
   end
 end
 
+def reset_i18n
+  I18n.backend = I18n::Backend::Simple.new
+end
+
 class Money
   module Warning
     def warn(message); end