Move schema.graphql file that is used everywhere to top dir

Rename the file from schema.graphqls to schema.graphql because it seems
to be a little more common and it's somewhat confusing to have a
different extension. I don't expect we will put query files in the top
level of the repository. See for a discussion:
99designs/gqlgen#1047 .

cleoc/gqclient/genqlient.yaml

@@ -1,6 +1,6 @@
 # Default genqlient config; for full documentation see:
 # https://github.com/Khan/genqlient/blob/main/docs/genqlient.yaml
-schema: ../../graph/schema.graphqls
+schema: ../../schema.graphql
 operations:
 - genqlient.graphql
 generated: generated.go

cleosrv/gqlgen.yml

@@ -1,6 +1,6 @@
 # Where are all the schema files located? globs are supported eg  src/**/*.graphqls
 schema:
-  - graph/*.graphqls
+  - ../schema.graphql
 
 # Where should the generated server code go?
 exec:

frontend/codegen.ts

@@ -1,7 +1,7 @@
 import { CodegenConfig } from '@graphql-codegen/cli';
 
 const config: CodegenConfig = {
-  schema: '../cleosrv/graph/schema.graphqls',
+  schema: '../schema.graphql',
   documents: ['src/**/*.tsx'],
   generates: {
     './src/__generated__/': {