M112-T131-A005 Process offset (skip) parameter for pagination

Framework was place in DatastoreQuery and PostgresQuery to accept the skip parameter, just adding the glue into discovery

M112
M112-T131-A002 Return total results available in DB

Flag available to only return the total results available in DB, no results are returned alongside

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M112-T134-A002 Testing return count, implemented with M112-T131-A002

Return value should only be a single value, the number of total results available in DB

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M112-T134-A002 Testing skip/offset parameter, implemented with M112-T131-A005

Return should differ when skip/offset parameter used

QueryLanguage had to be modified, was setting 'offset' value, 'skip' is word used by DatastoreQueryLanguage

These tests are still questionable, order_by parameter is not implemented in Datastore, pre-loads 200 values
so there would be a 1/200 chance the first result in non-skip query equals the 100th result if skip query. Need order implemented.

M112
M112-T131-A002 Return total results available in DB

input parameter count=True had to be changes to search_args={}

count request now passed in via search_args['count']=True

depends on https://github.com/ooici/ion-definitions/pull/487

M112
updates submodule reference

updates discovery interfaces

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Merge pull request #1773 from brianmckenna/m112_t131

CIDEVSTC-99: Directory service enhancements for count and skip