update nearcore to 2.7.0

[kobayurii]

This pull request updates the project to support NEAR v2.7.0 and Rust 1.86.0, along with several dependency upgrades and small code improvements to maintain compatibility with the latest NEAR ecosystem changes. It also adds documentation to clarify dependency management and branch usage.

Dependency and Environment Updates

• Updated all NEAR-related dependencies in Cargo.toml to use forks based on NEAR v2.7.0, and bumped the near-jsonrpc-client and near-lake-framework versions to match their latest forks.
• Raised the minimum required Rust version to 1.86.0 across Cargo.toml, rust-toolchain, and all Dockerfiles (rpc-server/Dockerfile, state-indexer/Dockerfile, tx-indexer/Dockerfile). [1] [2] [3] [4] [5]
• Updated the supported NEAR and Rust versions in CHANGELOG.md.

Documentation Improvements

• Added a new section to README.md describing branch usage, NEAR dependency management, and the rationale for using forks instead of crates.io releases.

Compatibility and Refactoring

• Refactored usage of NEAR epoch configuration in configuration/src/lib.rs and rpc-server/src/modules/network/methods.rs to use the new EpochConfigStore and AllEpochConfig::from_epoch_config_store APIs, ensuring compatibility with NEAR v2.7.0. [1] [2]
• Updated transaction handling in rpc-server/src/modules/transactions/methods.rs to match the new structure of TransactionInfo::Transaction in NEAR v2.7.0.

Feature Additions and Minor Fixes

• Implemented new methods in CodeStorage for handling global contract actions required by the updated NEAR VM runner API.
• Added support for new query types in rpc-server/src/modules/queries/methods.rs, with placeholder errors for unimplemented features (ViewGlobalContractCode, ViewGlobalContractCodeByAccountId). [1] [2]
• Minor code improvements and cleanups, such as simplifying SSL context creation and updating protocol version retrieval logic. [1] [2] [3] [4] [5]