fix(con cache): allow concache to accept ets options

[cking222]

Cache.ConCache exposes an ets_options config hook, but providing ets_options caused a compile-time failure during use Cache option validation (Cache.ETS.opts_definition/1 missing). This prevented callers from enabling ETS flags like read_concurrency / write_concurrency on ConCache tables.

PR also adds support for the :auto option on ETS table write_concurrency

Compiling 17 files (.ex)

== Compilation error in file lib/schema_cache/firestore/con_cache.ex ==
** (UndefinedFunctionError) function Cache.ETS.opts_definition/1 is undefined or private. Did you mean:

      * opts_definition/0

    (elixir_cache 0.3.12) Cache.ETS.opts_definition([read_concurrency: true, write_concurrency: false])
    (nimble_options 1.1.1) lib/nimble_options.ex:797: NimbleOptions.validate_type/3
    (nimble_options 1.1.1) lib/nimble_options.ex:562: NimbleOptions.validate_option/3
    (nimble_options 1.1.1) lib/nimble_options.ex:542: NimbleOptions.reduce_options/2
    (elixir 1.18.4) lib/enum.ex:4968: Enumerable.List.reduce/3
    (elixir 1.18.4) lib/enum.ex:2600: Enum.reduce_while/3
    (nimble_options 1.1.1) lib/nimble_options.ex:535: NimbleOptions.validate_options/2
    (nimble_options 1.1.1) lib/nimble_options.ex:508: NimbleOptions.validate_options_with_schema_and_path/3
    ```