Feat new space helpers

[mvandeberg]

Brief description

Note: this is a recreation of #13 due to erroneous closure.

Add 4 additional methods to the Space helper:

• getManyKeys: retrieves an array of keys from a space
• getManyValues: retrieves an array of values from a space
• getManyObjkeys: retrieves an array of proto object keys from a space
• getManyObjValues: retrieves an array of proto objects from a space

Checklist

• [x] I have built this pull request locally
• [x] I have ran the unit tests locally
• [x] I have manually tested this pull request
• [x] I have reviewed my pull request
• [x] I have added any relevant tests

Demonstration

see unit tests: https://github.com/koinos/koinos-sdk-as/blob/feat-new-space-helpers/__tests__/space.spec.ts

[Describe]: space

 [Success]: ✔ should put and get an object RTrace: +45
 [Success]: ✔ should check if space has an object or not RTrace: +37
 [Success]: ✔ should remove an object RTrace: +45
 [Success]: ✔ should get next and prev object RTrace: +124
 [Success]: ✔ should get many RTrace: +641

[Describe]: space with proto key

 [Success]: ✔ should put and get an object RTrace: +41
 [Success]: ✔ should check if space has an object or not RTrace: +37
 [Success]: ✔ should remove an object RTrace: +43
 [Success]: ✔ should get next and prev object RTrace: +124
 [Success]: ✔ should get many RTrace: +448

    [File]: /Users/rr/Documents/blockchain/koinos-sdk-as/__tests__/space.spec.ts
  [Groups]: 3 pass, 3 total
  [Result]: ✔ PASS
[Snapshot]: 0 total, 0 added, 0 removed, 0 different
 [Summary]: 10 pass,  0 fail, 10 total
    [Time]: 298.663ms