feat(template_lib): builtin template addresses

[mrnaveira]

Description

• template_lib exports an enum BuiltinTemplate that enumerates all the builtin templates and allows to retrieve the addresses via a new BuiltinTemplateInvoke engine operation
• The engine implements the EngineOp::BuiltinTemplateInvoke by accessing the appropriate constants in the template_builtin crate

Motivation and Context

Template developers will want to perform cross-template calls with builtin templates (e.g. accounts). For convenience we want to expose the corresponding template addresses in the template_lib crate.

There are two main ways of doing this:

1. Export the template addresses directly as constants
2. Create a new engine call for getting the template address

This PR follows (2) for template WASM size optimisation reasons, as (1) would require to include the full address (32 bytes for each one of the builtin templates, and we may have more of them in the future) in every template WASM.

How Has This Been Tested?

New engine unit test for builtin template addresses

What process can a PR reviewer use to test or verify this change?

Use the new BuiltinTemplate enum in a template

Breaking Changes

• None
• Requires data directory to be deleted
• Other - Please specify

[github-actions]

Test Results (CI)

194 tests  +1   194 ✅ +1   1h 36m 28s ⏱️ + 18m 53s
 52 suites ±0     0 💤 ±0 
  2 files   ±0     0 ❌ ±0 

Results for commit 52990bd. ± Comparison against base commit 6d30028.

♻️ This comment has been updated with latest results.

[sdbondi]

Looks good, could we also provide a method to fetch the currently executing template address in templates?