feat: add --experiments flag to replace --experimental (#5767)

- Deprecates the --experimental flag
- Adds a new flag --experiments which supports passing multiple comma-separated values or a wildcard value.
- Exposes a new endpoint /api/v2/experiments that returns the list of enabled experiments.
- Deprecates the field Features.Experimental in favour of this new API.
- Updates apidocgen to support type aliases (shoutout to @mtojek).
- Modifies apitypings to support generating slice types.
- Updates develop.sh to pass additional args after -- to $CODERD_SHIM.

scripts/apitypings/testdata/enums/enums.go

@@ -1,6 +1,7 @@
 package enums
 
 type Enum string
+type Enums []Enum
 
 const (
 	EnumFoo Enum = "foo"

scripts/apitypings/testdata/enums/enums.ts

@@ -1,5 +1,8 @@
 // Code generated by 'make site/src/api/typesGenerated.ts'. DO NOT EDIT.
 
+// From codersdk/enums.go
+export type Enums = Enum[]
+
 // From codersdk/enums.go
 export type Enum = "bar" | "baz" | "foo" | "qux"
 export const Enums: Enum[] = ["bar", "baz", "foo", "qux"]