use an option for schema version for create functions

[zkamvar]

In reichlab/variant-nowcast-hub#176, the workflow to create a new round began to fail because the default schema for functions like create_task_id is "latest" so it constructed a v4 schema instead of v3.0.1 resulting in the following error:

ℹ Existing config found, adding a new round
Error in `hubAdmin::append_round()`:
✖ Schema version mismatch between `config` and round.
! Must be the same.
• `config`:
  "https://raw.githubusercontent.com/hubverse-org/schemas/main/v3.0.1/tasks-schema.json"
• round:
  "https://raw.githubusercontent.com/hubverse-org/schemas/main/v4.0.0/tasks-schema.json"
Backtrace:
    ▆
 1. └─hubAdmin::append_round(existing_task_config, new_round)
 2.   └─cli::cli_abort(...) at hubAdmin/R/append_round.R:133:5
 3.     └─rlang::abort(...)

I think we should specify schema = getOption("hubAdmin.schema_version", default = "latest") in the function signatures, so that way users can specify one line at the top of their script to set the schema version while they are developing the script.

options(hubAdmin.schema_version = "v3.0.1")

[annakrystalli]

This is a great idea! Will implement!

[annakrystalli]

Will also include an option for branch