Hotfix: Consolidate parameters in one `constants.rs`

# Background

Parameter constants, with values set at compile time, are distributed across a variety of files in the runtime, and are hard to manage. Currently, constant parameters are distributed a variety of files, and intermingled with lots of other kinds of code, specifically files

* `lib.rs`
* `constants.rs`
* `proposal_configurations/mod.rs`
* `lock.rs`

# Proposal

At some point, we are going to just go full-on mutables, as is described here: https://github.com/Joystream/joystream/issues/4225, but I suspect that will take some more time to pull off, as it will have cascading consequences on other apps as well, so before that, lets just consolidate.

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