ref: remove all releases.js files and _common/ fetchers

These files are no longer loaded at runtime. All release data now comes
from _cache/YYYY-MM/{pkg}.json files generated by the Go webicached daemon.

Deleted:
- 94 {pkg}/releases.js files (per-package upstream fetchers)
- 8 _common/*.js files (github.js, gitea.js, git-tag.js, fetcher.js, etc.)

Updated:
- _webi/classify-one.js: reads from cache instead of require(releases.js)
- Fixed hardcoded triplet key to use dynamic lookup

sqlpkg/releases.js

@@ -1,19 +0,0 @@
-'use strict';
-
-var github = require('../_common/github.js');
-var owner = 'nalgeon';
-var repo = 'sqlpkg-cli';
-
-module.exports = function () {
-  return github(null, owner, repo).then(function (all) {
-    all._names = ['sqlpkg-cli', 'sqlpkg'];
-    return all;
-  });
-};
-
-if (module === require.main) {
-  module.exports().then(function (all) {
-    all = require('../_webi/normalize.js')(all);
-    console.info(JSON.stringify(all, null, 2));
-  });
-}