Support Go 1.18: Upgrade gqlgen to v0.17.2 (#2443)

* Upgrade gqlgen to v0.17.2

This enables builds on Go 1.18. github.com/vektah/gqlparser is upgraded
to the newest version too.

Getting this to work is a bit of a hazzle. I had to first remove
vendoring from the repository, perform the upgrade and then re-introduce
the vendor directory. I think gqlgens analysis went wrong for some
reason on the upgrade. It would seem a clean-room installation fixed it.

* Bump project to 1.18

* Update all packages, address gqlgenc breaking changes

* Let `go mod tidy` handle the go.mod file

* Upgrade linter to 1.45.2

* Introduce v1.45.2 of the linter

The linter now correctly warns on `strings.Title` because it isn't
unicode-aware. Fix this by using the suggested fix from x/text/cases
to produce unicode-aware strings.

The mapping isn't entirely 1-1 as this new approach has a larger iface:
it spans all of unicode rather than just ASCII. It coincides for ASCII
however, so things should be largely the same.

* Ready ourselves for errchkjson and contextcheck.

* Revert dockerfile golang version changes for now

Co-authored-by: Kermie <kermie@isinthe.house>
Co-authored-by: WithoutPants <53250216+WithoutPants@users.noreply.github.com>

vendor/github.com/99designs/gqlgen/plugin/servergen/server.go

@@ -1,13 +1,14 @@
 package servergen
 
 import (
+	"errors"
+	"io/fs"
 	"log"
 	"os"
 
 	"github.com/99designs/gqlgen/codegen"
 	"github.com/99designs/gqlgen/codegen/templates"
 	"github.com/99designs/gqlgen/plugin"
-	"github.com/pkg/errors"
 )
 
 func New(filename string) plugin.Plugin {
@@ -23,13 +24,14 @@ var _ plugin.CodeGenerator = &Plugin{}
 func (m *Plugin) Name() string {
 	return "servergen"
 }
+
 func (m *Plugin) GenerateCode(data *codegen.Data) error {
 	serverBuild := &ServerBuild{
 		ExecPackageName:     data.Config.Exec.ImportPath(),
 		ResolverPackageName: data.Config.Resolver.ImportPath(),
 	}
 
-	if _, err := os.Stat(m.filename); os.IsNotExist(errors.Cause(err)) {
+	if _, err := os.Stat(m.filename); errors.Is(err, fs.ErrNotExist) {
 		return templates.Render(templates.Options{
 			PackageName: "main",
 			Filename:    m.filename,