Rename default datasource (#1941)

* Rename default datasource

When looking in the documentation for experimental features (For example
using DB native types) you need to add a previewFeatures flag to the
Generate block, and then in the docs they use `@db.*` everywhere.

So as an example if you'd want to use the Postgres native Date field you
get something like this:

`createdAt DateTime @default(now()) @db.Date`

Since we use `DS`as a default datasource it can trip users up a bit
since `@DS.Date` is not a valid Prisma line (Somehow they don't like the
uppercase datasource).

So if we would already rename it to `datasource db {}` we would make it
easier for users in the future

* rename prisma datasource: docs, test, fixture, mod

Co-authored-by: David Price <thedavid@thedavidprice.com>

packages/cli/src/commands/generate/scaffold/__tests__/fixtures/schema.prisma

@@ -1,4 +1,4 @@
-datasource DS {
+datasource db {
   provider = "postgresql"
   url      = env("DB_HOST")
 }

packages/cli/src/commands/generate/sdl/__tests__/fixtures/schema.prisma

@@ -1,4 +1,4 @@
-datasource DS {
+datasource db {
   provider = "mysql"
   url      = env("DB_HOST")
 }

packages/cli/src/commands/generate/service/__tests__/fixtures/schema.prisma

@@ -1,4 +1,4 @@
-datasource DS {
+datasource db {
   provider = "postgresql"
   url      = env("DB_HOST")
 }

packages/cli/src/lib/__tests__/fixtures/schema.prisma

@@ -1,4 +1,4 @@
-datasource DS {
+datasource db {
   provider = "sqlite"
   url = env("DB_HOST")
 }

packages/create-redwood-app/template/api/db/schema.prisma

@@ -1,4 +1,4 @@
-datasource DS {
+datasource db {
   provider = "sqlite"
   url      = env("DATABASE_URL")
 }

tasks/e2e/cypress/integration/01-tutorial/codemods/Step4_1_DbSchema.js

@@ -1,7 +1,7 @@
 export default `
 // api/db/schema.prisma
 
-datasource DS {
+datasource db {
   provider = "sqlite"
   url      = env("DATABASE_URL")
 }