Update countries geojson file to use ONS BFE - #480

Update countries geojson file to use ONS BFE reduced to 5dp for server-side validation and simplified for use on the client

• Added new geojson file for countries data.
• Introduced a CountryMap object to map country names to their respective identifiers.
• Updated GeospatialCountriesQuery typedef to use keyof CountryMap for omit and only properties.

Proposed change

Fixes two issues, first that locations near the coast could be deemed outside the country due to clipping. This has been remedied by using the full BFE file for server-side validation.

The second issue is that inlets and rivers could be deemed outside the country. This is solved by moving the ONS BFE that clips to the mean low water mark. The following point on the Thames was previously deemed outside England.

This is now solved as the Thames is clipped:

Jira ticket: https://eaflood.atlassian.net/browse/DF-1508

Type of change

• Bug fix
• New feature
• Breaking change
• Misc. (documentation, build updates, etc)

Checklist

• You have executed this code locally and it performs as expected.
• You have added tests to verify your code works.
• You have added code comments and JSDoc, where appropriate.
• There is no commented-out code.
• You have added developer docs in README.md and docs/* (where appropriate, e.g. new features).
• The tests are passing (npm run test).
• The linting checks are passing (npm run lint).
• The code has been formatted (npm run format).