feat: proxy support

[topshihun]

Issue Link: #261

Changed files:

wiki-api/cargo.toml:

• Add feature "socks" for reqwest.

src/cli.rs:

• Add proxy: Option<String> for Cli struct.
• Add 'warn_list: Vec' for CliResults, because it can't use tracing and log when match cli and the operation of initial proxy maybe failed.
• Add proxy initial code in match_cli().

src/main.rs:

• Add code for warning CliResults.warn_list.

new file: wiki-api/src/proxy.rs

• static proxy: OnceLock<Proxy>: ensure proxy.
• 'fn validate_proxy` : check proxy address.
• pub fn init_proxy: initial proxy and it can only be used once.
• pub fn get_proxy: get proxy.

wiki-api/page.rs and wiki-api/search.rs

• replace Client::new to Client::builder and add proxy setting.