Postgraphile v5 Support (#58) - #66

After bumping to the v5 package versions, tests would fail with the
following error:

```
● Test suite failed to run

  ReferenceError: TextEncoder is not defined

  > 1 | import * as pg from "pg";
      | ^
    2 |
    3 | export async function withPgPool<T = any>(
    4 |   cb: (pool: pg.Pool) => Promise<T>

    at Object.<anonymous> (node_modules/pg/lib/crypto/utils-webcrypto.js:22:21)
    at Object.<anonymous> (node_modules/pg/lib/crypto/utils.js:8:20)
    at Object.<anonymous> (node_modules/pg/lib/crypto/sasl.js:2:16)
    at Object.<anonymous> (node_modules/pg/lib/client.js:5:12)
    at Object.<anonymous> (node_modules/pg/lib/index.js:3:14)
    at Object.<anonymous> (__tests__/helpers.ts:1:1)
    at Object.<anonymous> (__tests__/schema.minimal_type.test.ts:2:1)
```

Based on [information from @SimenB](
  jsdom/jsdom#2524 (comment)
), it seems like you probably should not be using
`jest-environment-jsdom` to start with if you need access to
`TextEncoder` or `TextDecoder`.

Based on [this](
  https://stackoverflow.com/a/72369912/1137077
) answer on SO, I was able to verify that `@jest-environment node` at
the top of test files fixed the issue. However, it would seem more
logical to apply this as a global setting, given that postgraphile is
meant to run in a node context.

After setting `testEnvironment: jest-environment-node` in the global
config, I found that tests again started failing. However, the new
failures seem related to the v5 changes to plugins which is expected at
this stage.

The previous `moduleResolution: node` setting prevent importing types
from `graphile-build-pg/pg-introspection`.

`NodeNext` was chosen based on
https://github.com/graphile/crystal/blob/91e87ab6516490a4cc7b7fc6400efb7623fbd331/graphile-build/graphile-build/tsconfig.json#L9

`postgraphile-core` is no more according to documentation:
https://postgraphile.org/postgraphile/next/migrating-from-v4/#postgraphile-core

This seems to be better in line with other v5 plugins and the new
`GraphileConfig.Preset` type.

npm/pnpm run the prepare lifecycle script (not prepack) when installing
a package directly from a git repository, since published tarballs
already ship a built dist/ but git checkouts don't. Without this,
depending on this branch directly (e.g. via a git URL) installs a
package with no dist/index.js.

…raphy columns

Two bugs found while investigating a reported GeoJSON input error:

1. PostgisColumnsPlugin's field plan assumed every record was a
   PgSelectSingleStep (which has `.select()`), but insert/update/delete
   mutation steps (PgInsertSingleStep/PgUpdateSingleStep/PgDeleteSingleStep)
   don't have that method - only `.get()`. So reading a geometry/geography
   field back from any create/update/delete mutation payload threw
   "$record.select is not a function". Fixed by branching on step type:
   `.select()` for queries (unchanged), and for mutations, build the same
   SQL expression via `pgClassExpression()` referencing the row's own
   `.alias` directly - the same approach these steps' own `.get()` uses for
   plain attributes.

2. The base geometry/geography codec's `toPg` was an identity function, so
   an incoming GeoJSON object (from the `GeoJSON` input scalar) was sent to
   Postgres as a JSON.stringify'd string. This happened to "work" for
   `geometry` columns only because `geometry_in` undocumentedly
   lenient-parses GeoJSON text - `geography_in` does not, and fails hard
   with "parse error - invalid geometry" (this was the actual server-side
   failure behind a mutation that looked, in GraphiQL/Ruru's variable
   editor, like a client-side "GeoJSON expects string/number/boolean"
   linter false positive - that lint warning is real but unrelated; this
   parse error is what actually broke the request). Added
   src/geoJsonToWkt.ts to convert GeoJSON to WKT/EWKT explicitly in `toPg`,
   which both `geometry_in` and `geography_in` accept identically -
   verified against Point, 3D Point (Z), LineString, Polygon, MultiPolygon,
   and GeometryCollection round-tripped through real create mutations.

All 65 existing tests still pass.