solana-type-overrides is causing dependency bloat

[kevinheavey]

Problem

solana-type-overrides was added to multiple crates in #1634

The following crates do not use futures but because they depend on solana-type-overrides they now depend on futures:

• solana-program-runtime
• solana-bpf-loader-program
• solana-loader-v4-program
• solana-stake-program
• solana-system-program
• solana-svm

Proposed Solution

Move solana_type_overrides::executor to a new crate

[LucasSte]

Move solana_type_overrides::executor to a new crate

Instead of creating a new crate, we can mark futures as an optional decency and put the executor module behind a cfg feature. This way, crates that need the module import type_overrides with the feature enabled and the dependency is only built when necessary.

[kevinheavey]

Crates are friendlier to parallel builds and have fewer footguns like failing to check a feature in CI