Allow ability to skip checks against schema in as_config() checks

[annakrystalli]

Backrgound

Currently there are a bunch of check performed during as_config().

1. Check the schema_id prefix url
2. Check the schema_id version is a valid released version (requires internet connection - annoying during new schema version development)
3. Check config level 1 property names against schema (requires internet connection and valid schema_id to download schema)
4. Check that the schema file name can be parsed correctly to extract the config type

Performing these checks when coercing a list in R seems sensible, but requiring an internet connection and re-performing checks that should have been performed vi validate_config() to just load a json config file seems excessive.

Proposal

• At the very least I feel we should be able to bypass checks 2 & 3 with a skip_schema_checks argument in as_config() that is set to TRUE when using as_config() as part of read_config_file().
• Check 3 should only deploy if check 2 is successful

Open to suggestions for cleaner more intuitive approaches.

Relatedly, if any errors are thrown in as_config(), the read_config() and read_config_file() still fail to return a config class object, however they now it do so silently by default. Is this the desired behaviour? If not, what is the desired behaviour?