Update endpoint URLs from the DataImport→Process rename

backend#1304 (closed) has a significant impact on all the API requests cluttered in src/api.js. The following endpoints have updated URLs:

ClearProcess
CreateDataFile
CreateElementsWorkflow
CreateExternalRepository
CreateFilesProcess
CreateImportTranskribus
CreateWorkerRun
DestroyDataFile
DestroyProcess
DestroyRepository
DestroyWorkerRun
ListDataFile
ListExternalRepositories
ListProcesses (which is also unnecessarily duplicated as listTemplates)
ListRepositories
ListWorkerRuns
PartialUpdateDataFile
PartialUpdateProcess
PartialUpdateWorkerRun
RetrieveProcess
RetrieveRepository
RetryProcess
StartProcess