fix: Prevent slugs with trailing slashes for non-container resources

* fix: slugs ending on slash with link header cannot create containers

* refactor(DataAccessorBasedStore): removing duplicate code and errors

* test(ServerFetch): fix integration tests that create a container

* fix: Reinstate original checks in setResource to let tests succeed

* test: change to container paths to end in / on POST only

* refactor: incorporate review changes

* fix: Error check was too strict

Co-authored-by: Joachim Van Herwegen <joachimvh@gmail.com>

* test: make testcase to test allowed slash behaviour

* test: removed unnecessary code from tests

* test: remove metadata line and duplicate tests

Co-authored-by: Joachim Van Herwegen <joachimvh@gmail.com>

test/integration/ServerFetch.test.ts

@@ -1,5 +1,6 @@
 import fetch from 'cross-fetch';
 import type { App } from '../../src/init/App';
+import { LDP } from '../../src/util/Vocabularies';
 import { getPort } from '../util/Util';
 import { getDefaultVariables, getTestConfigPath, instantiateFromConfig } from './Config';
 
@@ -112,6 +113,7 @@ describe('A Solid server', (): void => {
       headers: {
         'content-type': 'text/turtle',
         slug: 'containerPOST/',
+        link: `<${LDP.Container}>; rel="type"`,
       },
       body: '<a:b> <a:b> <a:b>.',
     });