strict mode enabled, removed duplicate sub-rules from tsconfig

[evwilkin]

What:
Closes #3223
Closes #3230

This PR enables strictNullChecks and strictPropertyInitialization.

These were the only sub-rules of strict mode that were disabled, so this also cleans up tsconfig by removing unnecessary sub-rules in favor of simply strict: true:

noImplicitAny
noImplicitThis
alwaysStrict
strictBindCallApply
strictNullChecks
strictFunctionTypes
strictPropertyInitialization

Additional issues:
Follow-up to work done in #4019
Enabled by updates to react-charts in #4138

[patternfly-build]

PF4 preview: https://patternfly-react-pr-4156.surge.sh
A11y report: https://patternfly-react-pr-4156-coverage.surge.sh

[patternfly-build]

Your changes have been released in:

• @patternfly/react-catalog-view-extension@4.2.10
• @patternfly/react-core@4.9.4
• @patternfly/react-docs@5.2.14
• @patternfly/react-icons@4.2.4
• @patternfly/react-inline-edit-extension@4.3.10
• demo-app-ts@4.6.7
• @patternfly/react-integration@4.6.2
• @patternfly/react-table@4.3.10
• @patternfly/react-topology@4.2.10
• @patternfly/react-virtualized-extension@4.2.10

Thanks for your contribution! 🎉