feat: add no-build option for fee::Args

[willemneal]

Fixes #1265.
Requires: #1173

Commands that build transactions now include the following args to output and exit early:

• --build-only prints the base64 xdr before simulation
• --sim-only prints the base64 xdr after simulation

For example,

soroban contract invoke --build-only .. -- hello --world world

prints:
AAAAAMwWyQMtAWO6nW4s+cKMRunx+kiaKfjJwIRNZEEclDvRAAAAZAAIgAEAAAANAAAAAAAAAAAAAAABAAAAAAAAABgAAAAAAAAAAQ3DO777M8sdGtPbMau+cuxAles4UILfUkZXOWTsqKvOAAAABWhlbGxvAAAAAAAAAQAAAA8AAAAFd29ybGQAAAAAAAAAAAAAAA==

soroban contract invoke --sim-only .. -- hello --world world

AAAAAMwWyQMtAWO6nW4s%2BcKMRunx%2BkiaKfjJwIRNZEEclDvRAAD4WAAIgAEAAAANAAAAAAAAAAAAAAABAAAAAAAAABgAAAAAAAAAAQ3DO777M8sdGtPbMau%2BcuxAles4UILfUkZXOWTsqKvOAAAABWhlbGxvAAAAAAAAAQAAAA8AAAAFd29ybGQAAAAAAAAAAAAAAQAAAAAAAAACAAAABgAAAAENwzu%2B%2BzPLHRrT2zGrvnLsQJXrOFCC31JGVzlk7KirzgAAABQAAAABAAAAB3mMSQSdZWZNBqeYQchZLRMLUhSFaxsEJAOkX%2Bel%2B%2BMzAAAAAABcQYMAABsoAAAAAAAAAAAAANeQ

Transaction result

The NetworkRunable trait a result type of TxnResult, either a raw xdr string or a T. This allows returning early.

update is-view

Ensure that is-view doesn't fetch account info as a source account doesn't need to exist for a simulation.

[leighmcculloch]

That was fast! This is great 👏🏻.

Couple questions inline.

The --sim-only might be unnecessary, given that folks could do soroban contract deploy --build-only | soroban tx simulate in the future, and that leans on command composability and keeps the options simpler. Thoughts from others on this? cc @fnando @chadoh

[leighmcculloch]

Will take another look once #1173 is merged, but this looked good when I last reviewed other than the couple minor things which are addressed so I think we'll be able to fast merge this once the other is on its way.

[leighmcculloch]

Few questions inline. Looks like this isn't far off.

[leighmcculloch]

I pushed a couple changes to the PR in the last 3 commits, and I left comments inline to outline why. Please take a look and let me know if you agree with them.

[leighmcculloch]

@willemneal If you're good with the changes I pushed, can you resolve the unresolved conversations which are just the notes I left explaining why each change, and once they're all resolved that should trigger GitHub to auto-merge the PR.

If possible don't force push the branch in case we need to make more changes.

[leighmcculloch]

I pushed a bug fix in 457a54b for how sim only works with install. I left a comment in the code about it for more information.