Split out ability to upload flyover data from pool uploads

Tons of changes here, all in the name of quickly getting to where I can
create test compliance letters.

db/migrations/00076_func_gen_alpha_code.sql

@@ -0,0 +1,16 @@
+-- +goose Up
+-- +goose StatementBegin
+CREATE OR REPLACE FUNCTION generate_alphanumeric_code(code_length INTEGER DEFAULT 8)
+RETURNS TEXT AS $$
+DECLARE
+    chars TEXT := 'ABCDEFGHJKMNPQRSTUVWXYZ23456789';
+    result TEXT := '';
+    i INTEGER;
+BEGIN
+    FOR i IN 1..code_length LOOP
+        result := result || substr(chars, floor(random() * length(chars) + 1)::INTEGER, 1);
+    END LOOP;
+    RETURN result;
+END;
+$$ LANGUAGE plpgsql;
+-- +goose StatementEnd