Package clean up

[sergesemashko]

• Add github actions integration

@Qunapi, please address:

• TODOs left in the code once the PR is merged
• There are lint warnings and a broken test:

/Users/sis/Sites/gitdb/src/CollectionStrategies/FileStrategy.test.ts
  130:22  warning  Missing return type on function           @typescript-eslint/explicit-function-return-type
  130:26  warning  Unexpected any. Specify a different type  @typescript-eslint/no-explicit-any

/Users/sis/Sites/gitdb/src/CollectionStrategies/FileStrategy.ts
  58:28  warning  Unexpected any. Specify a different type  @typescript-eslint/no-explicit-any

/Users/sis/Sites/gitdb/src/CollectionStrategies/MemoryStrategy.ts
  9:17  warning  Unexpected any. Specify a different type  @typescript-eslint/no-explicit-any

/Users/sis/Sites/gitdb/src/GitDB/GitDB.ts
   21:41  warning  Unexpected any. Specify a different type  @typescript-eslint/no-explicit-any
   48:50  warning  Unexpected any. Specify a different type  @typescript-eslint/no-explicit-any
  125:11  warning  'sha' is assigned a value but never used  @typescript-eslint/no-unused-vars
  133:22  warning  'files' is defined but never used         @typescript-eslint/no-unused-vars

/Users/sis/Sites/gitdb/src/GitDB/gitdb.test.ts
   85:55  warning  Unexpected any. Specify a different type  @typescript-eslint/no-explicit-any
  201:55  warning  Unexpected any. Specify a different type  @typescript-eslint/no-explicit-any

/Users/sis/Sites/gitdb/src/utils/file.ts
   9:12  warning  Unexpected any. Specify a different type  @typescript-eslint/no-explicit-any
  16:70  warning  Unexpected any. Specify a different type  @typescript-eslint/no-explicit-any
  28:17  warning  Unexpected any. Specify a different type  @typescript-eslint/no-explicit-any

✖ 13 problems (0 errors, 13 warnings)