CI: add check for explicit spl-token-cli version

[CriesofCarrots]

Problem

If https://github.com/solana-labs/solana-program-library releases a new version of spl-token-cli that depends on the beta branch, this cargo-install-all command will likely break, due to rust-version and various other mismatches.

Summary of Changes

Require the stable channel to set an explicit $splTokenCliVersion
Check that this is set in CI
Use $splTokenCliVersion to set a --version for the spl-token-cli cargo install command

Will fix #34429, with backports and (on v1.16) variable population

[CriesofCarrots]

Sorry about the premature review request. Just appeasing shellcheck

[t-nelson]

looks great! r+ ci

cc/ @yihau

[mergify]

Backports to the stable branch are to be avoided unless absolutely necessary for fixing bugs, security issues, and perf regressions. Changes intended for backport should be structured such that a minimum effective diff can be committed separately from any refactoring, plumbing, cleanup, etc that are not strictly necessary to achieve the goal. Any of the latter should go only into master and ride the normal stabilization schedule.

[mergify]

Backports to the beta branch are to be avoided unless absolutely necessary for fixing bugs, security issues, and perf regressions. Changes intended for backport should be structured such that a minimum effective diff can be committed separately from any refactoring, plumbing, cleanup, etc that are not strictly necessary to achieve the goal. Any of the latter should go only into master and ride the normal stabilization schedule. Exceptions include CI/metrics changes, CLI improvements and documentation updates on a case by case basis.

[willhickey]

Just confirming the expected process...

After a new minor version branch is created, PRs against the new-stable will fail until we update scripts/spl-token-cli-version.sh in that new-stable branch to pin a version here:
splTokenCliVersion=

If that's correct then this won't break any of the existing processes.

[CriesofCarrots]

After a new minor version branch is created, PRs against the new-stable will fail until we update scripts/spl-token-cli-version.sh in that new-stable branch to pin a version here:
splTokenCliVersion=

Yes, that's correct. Thanks for assessing, @willhickey !
Is populating $splTokenCliVersion something that makes sense for the minor-version branch creator to do? Or do we just let it be everyone's problem?

[CriesofCarrots]

@t-nelson , do you mind re-approving? I can't approve Will's release.md change

[yihau]

🫶

[CriesofCarrots]

Thanks @yihau !!