Implement OP_CHECKTEMPLATEVERIFY

[reardencode]

This pull request forks from #29198 and only includes the implementation of OP_CHECKTEMPLATEVERIFY, its tests (except the functional ones), and standardization of bare OP_CHECKTEMPLATEVERIFY locking scripts.

[DrahtBot]

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Type	Reviewers
Concept ACK	moonsettler

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Conflicts

Reviewers, this pull request conflicts with the following ones:

• #29843 (policy: Allow non-standard scripts with -acceptnonstdtxn=1 (test nets only) by ajtowns)
• #29270 (Implement OP_CHECKSIGFROMSTACK(VERIFY) by reardencode)
• #29269 (Add OP_INTERNALKEY for Tapscript by reardencode)
• #29247 (Reenable OP_CAT by 0xBEEFCAF3)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

[moonsettler]

Concept ACK!

[earonesty]

Lgtm. It's the simplest and least controversial and has an extremely broad use case set (not perfect for anything but useful for everything). No need to bikeshed if it's the best. It's useful and we need more useful things.