Block reload config files in Railtie if they already uploaded

[Nuzair46]

Continuation for #353
Fixes #352

[Nuzair46]

@pkuczynski @vovanmozg @Fryguy
Please take a look at this PR.
Its continuing the work by @vovanmozg in #353

[Copilot]

Pull Request Overview

This PR blocks the reloading of configuration files in the Rails Railtie if they have already been uploaded, preventing duplicate loading of settings. The change adds a guard clause to check if the configuration constant is already defined before proceeding with the default configuration loading.

Key changes:

• Added guard clause in Railtie to prevent duplicate config loading
• Enhanced test coverage for Rails context configuration scenarios
• Updated documentation to clarify custom settings file loading

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
lib/config/integrations/rails/railtie.rb	Added guard clause to prevent reloading if config constant already exists
spec/config_spec.rb	Added comprehensive test suite for Rails context configuration loading
spec/config_env_spec.rb	Added ENV backup/restore functionality for test isolation
spec/app/rails_*/config/boot.rb	Added logger requirement across Rails test apps
spec/app/rails_5.2/config/application.rb	Commented out config_available? call for test context
README.md	Added documentation for custom settings file loading

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[Copilot]

The Rails version check using string comparison is fragile. Consider using Gem::Version.new(Rails.version) >= Gem::Version.new('6.1.0') for more robust version comparison.

Suggested change

	File.write(spring_file_name_for_rails_6_1, "") if Rails.version.start_with?("6.1")
	File.write(spring_file_name_for_rails_6_1, "") if Gem::Version.new(Rails.version) >= Gem::Version.new('6.1.0')

[Copilot]

Using backticks for command execution can be unsafe and harder to test. Consider using system commands with proper error handling or mocking the Rails runner behavior in tests.

Suggested change

	values = `#{Rails.root.join("bin", "rails")} runner 'print "\#{Settings.default}|\#{Settings.custom}"'`
	stdout, status = Open3.capture2("#{Rails.root.join("bin", "rails")} runner 'print \"#{Settings.default}|#{Settings.custom}\"'")
	values = stdout
	expect(values).to eq("default_value|")
	end
	it "should read value only from default settings without use of load_and_set_settings" do
	File.write(config_name, "Config.setup { |config| }")
	stdout, status = Open3.capture2("#{Rails.root.join("bin", "rails")} runner 'print \"#{Settings.default}|#{Settings.custom}\"'")
	values = stdout
	expect(values).to eq("default_value|")
	end
	it "should read value only from custom settings with use of load_and_set_settings" do
	File.write(config_name, "Config.setup { |config| config.load_and_set_settings(['#{custom_settings_file_name}']) }")
	stdout, status = Open3.capture2("#{Rails.root.join("bin", "rails")} runner 'print \"#{Settings.default}|#{Settings.custom}\"'")
	values = stdout