Rename Balance::claimable_amount_satoshis to have a unique name

[TheBlueMatt]

In Java/TypeScript, we map enums as a base class and each variant as a class which extends the base. In Java/TypeScript, functions and fields share the same namespace, which means we cannot have functions on an enum which have the same name as any fields in any enum variants.

Balance's claimable_amount_satoshis method aliases with fields in each variant, and thus ultimately doesn't compile in TypeScript.

Because Balance::claimable_amount_satoshis has the same name as the fields, it's also a bit confusing, as it doesn't return the field for each variant, but sometimes returns zero if we're not sure we can claim the balance.

Instead, we rename the method
definitely_claimable_amount_satoshis.

[codecov-commenter]

Codecov Report

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2460      +/-   ##
==========================================
+ Coverage   90.33%   90.47%   +0.13%     
==========================================
  Files         106      106              
  Lines       55732    56612     +880     
  Branches    55732    56612     +880     
==========================================
+ Hits        50347    51218     +871     
- Misses       5385     5394       +9     

Files Changed	Coverage Δ
lightning/src/chain/channelmonitor.rs	94.82% <0.00%> (ø)

... and 2 files with indirect coverage changes

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[tnull]

Makes sense, but if I'd be reading definitely_claimable_amount_satoshis I may be somewhat confused what it does, I guess due to the colloquial language?

Maybe we could make it more expressive, e.g., something like infallibly_claimable_amount_satoshis or ensured_claimable_amount_satoshis?

[TheBlueMatt]

Yea, I'm not super happy with definitely, either, tbh. That said, I'm not sure I like infallibly or ensured a hell of a lot more - all three imply a surety level that isn't really guaranteed - balances which are "ours" still actually have to be claimed, which could fail if we lose a broadcast race. Now, I'm not sure users need to concern themselves with that, its ultimately our responsibility, but infallible seems like a very strong word, ensured too. The other option is to rename the fields in the enum variants to something other than claimable_amount, maybe we could just drop the claimable there, leave them all as amount_satoshis, and then have claimable_amount_satoshis be as-is?

[valentinewallace]

I vote removing the claimable_ prefixes from the Balance variant fields

[TheBlueMatt]

Done.