Add opcm upgrades spec (#468)

* Add opcm upgrades spec

* Reorganize OPCM spec around deploy vs. upgrade sections

* update OPCM getters

* Add `addGameType` section

* update toc

* feat: Update Deployed event to match impl

* fix lint

* fix the spec for the addGameType function

* Apply suggestions from code review

Co-authored-by: blaine <[email protected]>

* fixes

* Apply suggestions from code review

* lint

* fix lint

* remove info about specific deployments

* fix interface

* Improve readability of create2 input description

* add lang annotation to code fences

* Add DeployInput definition

* fix DeployInput and Roles struct definition

* Update addGameType spec

* feat: Update salt generation

* Fix interface casing

* lint

* Update specs/experimental/op-contracts-manager.md

* Add context on Upgrader role to intro

* Define IsthmusConfig and update addGameType config sources

* lint

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Co-authored-by: blaine <[email protected]>