List file support

[avanaur]

A brief description of the changes in this PR:

Support listing of file and not just directory on zbox list

Resolves 0chain/blobber#699

Tasks to complete before merging PR:

• Ensure system tests are passing. If not Run them manually to check for any regressions 📋
• Do any new system tests need added to test this change? do any existing system tests need updated? If so create a PR at 0chain/system_test
• Merge your system tests PR to master AFTER merging this PR

Associated PRs (Link as appropriate):

• 0chain:
• blobber: List file support blobber#730
• gosdk:
• system_test: List file support system_test#306
• zwalletcli:
• Other: ...

[service-0chain]

Manual system tests [failure] with the following config

config	value
tests skipped	FALSE
system-tests	feature/list-file
gosdk	staging
zboxcli	feature/list-file
zwalletcli	staging
0chain	staging
blobber	feature/list-file
authorizer	staging
0box	staging
0block	staging
0dns	staging
explorer	staging
0proxy	staging
0search	staging

[service-0chain]

Manual system tests [success] with the following config

config	value
tests skipped	FALSE
system-tests	feature/list-file
gosdk	staging
zboxcli	feature/list-file
zwalletcli	staging
0chain	staging
blobber	feature/list-file
authorizer	staging
0box	staging
0block	staging
0dns	staging
explorer	staging
0proxy	staging
0search	staging

[peterlimg]

lgtm

[service-0chain]

Manual system tests [success] with the following config

config	value
tests skipped	TRUE
system-tests	master
gosdk	staging
zboxcli	feature/list-file
zwalletcli	staging
0chain	staging
blobber	staging
authorizer	staging
0box	staging
0block	staging
0dns	staging
explorer	staging
0proxy	staging
0search	staging