refactor: rename swap fee to spread factor

[p0mvn]

Closes: #XXX

What is the purpose of the change

We offer a zero exchange fee from launch. Having the "swap fee" is misleading.

Partial quote from Sunny:

In an orderbook, the market makers get paid, not via an explicit fee, but via spread on the orderbook. In AMMs (including CL), we also effectively have a “spread”. Instead, we should be calling this a “spread factor”. Especially since CL is just a continuous form of orderbooks. The spread factor is a property of the pool that defines what spread the LPs are market making around.

This PR does the rename by:

• rename "swapFee" -> "spreadFactor"
• rename "swap fee" -> "spread factor"
• rename "SwapFee" -> "SpreadFactor"
• rename "swap-fee" -> "spread-factor"
• rename "swap_fee" -> "spread_factor"

At the same time, it avoids:

• state-breaks
• CLI breaks
• Message breaks
• Query breaks

As a result, some of the client-facing CLI, query, message, pool model and pool params logic still calls it "swap fee"

Next Steps (separate PR)

#5243

How To Review

• Skim but pay attention to:

• No message breaks
• No state breaks
• No event breaks
• No query breaks

Testing and Verifying

This change is a trivial rework / code cleanup without any test coverage.

Documentation and Release Note

• Does this pull request introduce a new feature or user-facing behavior changes? no
• Is a relevant changelog entry added to the Unreleased section in CHANGELOG.md? no
• How is the feature or change documented? not applicable

[AlpinYukseloglu]

LGTM on a quick skim (leaning heavily on the assumption that CI would catch any breaking issues related to find and replace)

Did notice that CL fee related naming is still pretty centered on "fee" terminology (e.g. feeAccumulator) but this might be trickier to replace

[p0mvn]

Did notice that CL fee related naming is still pretty centered on "fee" terminology (e.g. feeAccumulator) but this might be trickier to replace

Yes, planning to address this in: #5243

[p0mvn]

Merging simple rename. Discussed further work for #5243 offline