DB2Rest and tests should be agnostic of FileSystem used (Windows, Linux, etc.)

[thadguidry]

Currently tests will fail on Windows systems (maybe others) because of path errors such as:

[ERROR]   PgJsonFileCreateControllerTest.createDirectorViaUpload:71 »
   InvalidPath Illegal char <:> at index 2: /F:/GitHubRepos/db2rest/api-rest/target/test-classes/testdata/director.json

This is because we're not agnostic enough for the filesystem through java.nio methods.
According to docs for java.nio.file.Path.of(), we should be agnostic of filesystems since we are providing a library, and instead use an existing Path instance as an anchor as explained:

The Path is obtained by invoking the getPath method of the default FileSystem.

Note that while this method is very convenient, using it will imply an assumed reference to the default FileSystem and limit the utility of the calling code. Hence it should not be used in library code intended for flexible reuse. A more flexible alternative is to use an existing Path instance as an anchor, such as:

Path dir = ...
Path path = dir.resolve("file");

[thadguidry]

Full log of current ERRORS on Windows building:

[ERROR]   MySQLJsonFileCreateControllerTest.createDirectorViaUpload:71 » InvalidPath Illegal char <:> at index 2: /F:/GitHubRepos/db2rest/api-rest/target/test-classes/testdata/director.json     
[ERROR]   MySQLJsonFileCreateControllerTest.createFilmsViaUpload:91 » InvalidPath Illegal char <:> at index 2: /F:/GitHubRepos/db2rest/api-rest/target/test-classes/testdata/BULK_CREATE_FILM_REQUEST.json
[ERROR]   MySQLJsonFileCreateControllerTest.uploadActorFileNonJsonArray:56 » InvalidPath Illegal char <:> at index 2: /F:/GitHubRepos/db2rest/api-rest/target/test-classes/testdata/CREATE_ACTOR_REQUEST.json
[ERROR]   MySQLJsonFileCreateControllerTest.uploadActorsFile:36 » InvalidPath Illegal char <:> at index 2: /F:/GitHubRepos/db2rest/api-rest/target/test-classes/testdata/actor.json
[ERROR]   OracleJsonFileCreateControllerTest.createDirectorViaUpload:71 » InvalidPath Illegal char <:> at index 2: /F:/GitHubRepos/db2rest/api-rest/target/test-classes/testdata/director.json    
[ERROR]   OracleJsonFileCreateControllerTest.createFilmsViaUpload:91 » InvalidPath Illegal char <:> at index 2: /F:/GitHubRepos/db2rest/api-rest/target/test-classes/testdata/BULK_CREATE_FILM_REQUEST.json
[ERROR]   OracleJsonFileCreateControllerTest.uploadActorFileNonJsonArray:56 » InvalidPath Illegal char <:> at index 2: /F:/GitHubRepos/db2rest/api-rest/target/test-classes/testdata/CREATE_ACTOR_REQUEST.json
[ERROR]   OracleJsonFileCreateControllerTest.uploadActorsFile:36 » InvalidPath Illegal char <:> at index 2: /F:/GitHubRepos/db2rest/api-rest/target/test-classes/testdata/actor.json
[ERROR]   PgJsonFileCreateControllerTest.createDirectorViaUpload:71 » InvalidPath Illegal char <:> at index 2: /F:/GitHubRepos/db2rest/api-rest/target/test-classes/testdata/director.json        
[ERROR]   PgJsonFileCreateControllerTest.createFilmsViaUpload:91 » InvalidPath Illegal char <:> at index 2: /F:/GitHubRepos/db2rest/api-rest/target/test-classes/testdata/BULK_CREATE_FILM_REQUEST.json
[ERROR]   PgJsonFileCreateControllerTest.uploadActorFileNonJsonArray:56 » InvalidPath Illegal char <:> at index 2: /F:/GitHubRepos/db2rest/api-rest/target/test-classes/testdata/CREATE_ACTOR_REQUEST.json
[ERROR]   PgJsonFileCreateControllerTest.uploadActorsFile:36 » InvalidPath Illegal char <:> at index 2: /F:/GitHubRepos/db2rest/api-rest/target/test-classes/testdata/actor.json
[INFO]
[ERROR] Tests run: 342, Failures: 6, Errors: 70, Skipped: 9