fix: add ToString for no_std add exports some types in no_std

[yjhmelody]

Seems some versions of rust need this.

error[E0599]: no method named `to_string` found for reference `&'static str` in the current scope
   --> /Users/yjhmelody/.cargo/registry/src/index.crates.io-6f17d22bba15001f/revm-6.1.0/src/optimism/handler_register.rs:187:68
    |
187 |                 "[OPTIMISM] Failed to load enveloped transaction.".to_string(),
    |                                                                    ^^^^^^^^^ method not found in `&str`
    |
    = help: items from traits can only be used if the trait is in scope
help: the following trait is implemented but not in scope; perhaps add a `use` for it:
    |
3   + use crate::std::string::ToString;
    |

error[E0599]: no method named `to_string` found for reference `&'static str` in the current scope
   --> /Users/yjhmelody/.cargo/registry/src/index.crates.io-6f17d22bba15001f/revm-6.1.0/src/optimism/handler_register.rs:228:67
    |
228 |                 "[OPTIMISM] Failed to load L1 block information.".to_string(),
    |                                                                   ^^^^^^^^^ method not found in `&str`
    |
    = help: items from traits can only be used if the trait is in scope
help: the following trait is implemented but not in scope; perhaps add a `use` for it:
    |
3   + use crate::std::string::ToString;
    |

error[E0599]: no method named `to_string` found for reference `&'static str` in the current scope
   --> /Users/yjhmelody/.cargo/registry/src/index.crates.io-6f17d22bba15001f/revm-6.1.0/src/optimism/handler_register.rs:234:68
    |
234 |                 "[OPTIMISM] Failed to load enveloped transaction.".to_string(),
    |                                                                    ^^^^^^^^^ method not found in `&str`
    |
    = help: items from traits can only be used if the trait is in scope
help: the following trait is implemented but not in scope; perhaps add a `use` for it:
    |
3   + use crate::std::string::ToString;
    |

error[E0599]: no method named `to_string` found for reference `&'static str` in the current scope
   --> /Users/yjhmelody/.cargo/registry/src/index.crates.io-6f17d22bba15001f/revm-6.1.0/src/optimism/handler_register.rs:247:67
    |
247 |                 "[OPTIMISM] Failed to load L1 Fee Vault account.".to_string(),
    |                                                                   ^^^^^^^^^ method not found in `&str`
    |
    = help: items from traits can only be used if the trait is in scope
help: the following trait is implemented but not in scope; perhaps add a `use` for it:
    |
3   + use crate::std::string::ToString;
    |

error[E0599]: no method named `to_string` found for reference `&'static str` in the current scope
   --> /Users/yjhmelody/.cargo/registry/src/index.crates.io-6f17d22bba15001f/revm-6.1.0/src/optimism/handler_register.rs:260:69
    |
260 |                 "[OPTIMISM] Failed to load Base Fee Vault account.".to_string(),
    |                                                                     ^^^^^^^^^ method not found in `&str`
    |
    = help: items from traits can only be used if the trait is in scope
help: the following trait is implemented but not in scope; perhaps add a `use` for it:
    |
3   + use crate::std::string::ToString;
    |

For more information about this error, try `rustc --explain E0599`.
error: could not compile `revm` (lib) due to 5 previous errors
warning: build failed, waiting for other jobs to finish...

And some types should also work in no_std.

[rakita]

nice one!