chore: refresh README/SECURITY.md and harden npm install-script policy

[Redtigercod4]

Summary

Refreshed documentation relevant to the development and overview of PulpUI, this now includes the governance documentation needed on this repository aligned to the Pulp organisation. This update does also address all known npm audit vulnerabilities with package updates to webpack. Finally, it also includes a hardened .npmrc file to mitigate potential attack vectors recently found in Shai-Hulud type attacks.

Changes

1. Refreshed README.md with better guidance and overview of the application.
2. Added SECURITY.md aligned to the new Pulp Governance requirements at the organisation level.
3. Hardened .npmrc configuration with best practices to mitigate any Shai-Hulud or wider attacks.
4. Bumped associated packages to address all vulnerabilities highlighted in npm audit.

Out of Scope

1. Documentation changes to Pulp Docs related to PulpUI

Blockers

N/A

Linked issue

N/A

Sources

1. https://github.com/pulp/governance
2. https://snyk.io/articles/npm-security-best-practices-shai-hulud-attack/

[ggainey]

The docs-updates are especially welcome - thank you for thorough work here.