Refactor namespaces, bump version, enforce type strictness

[chrismccluskey]

Changes proposed in this Pull Request

• Refactor namespaces to remove duplication
• Bumps version to 1.0.0
• Enforces type strictness by making sure all files include declare( strict_types=1 ); unless they are empty index files.
• Fix issue with $login event
• Fix some issues that came up from enforcing type strictness

Testing instructions

Automated tests should cover this. Otherwise, a full test would look like the following:

• Start the environment
• Active the sift-for-woocommerce plugin
• Navigate to the settings page and enter your sift sandbox mode API key, beacon key and account id.
• Try triggering various events (e.g., login, logout, creating orders..) and check the sift dashboard to see if the events were sent successfully.

Closes 548-gh-automattic/gold

[github-actions]

Package	Line Rate	Complexity	Health
inc/abuse-decisions-actions.php	0%	22	❌
inc/abuse-decisions.php	0%	12	❌
inc/payment-gateway.php	100%	5	✔
inc/payment-gateways/index.php	0%	0	❌
inc/payment-gateways/lib/stripe.php	77%	61	✔
inc/payment-gateways/load.php	0%	0	❌
inc/payment-gateways/paypal.php	0%	0	❌
inc/payment-gateways/stripe.php	23%	17	❌
inc/payment-gateways/transact.php	100%	0	✔
inc/payment-gateways/woocommerce-payments.php	100%	0	✔
inc/payment-method.php	97%	31	✔
inc/payment-type.php	83%	3	✔
inc/rest-api-webhooks.php	0%	5	❌
inc/sift-object-validator.php	89%	130	✔
inc/sift-order.php	100%	4	✔
inc/sift-property.php	100%	3	✔
inc/tracking-js.php	0%	4	❌
inc/verification-status.php	50%	3	➖
inc/wc-settings-tab.php	0%	14	❌
inc/woocommerce-actions.php	70%	93	➖
index.php	0%	0	❌
sift-for-woocommerce.php	0%	9	❌
Summary	63% (917 / 1464)	416	➖

[millerf]

LGTM!