Add support to use rustls with azure-identity (#517)

Author: bmc-msft

sdk/identity/Cargo.toml

@@ -13,15 +13,15 @@ categories = ["api-bindings"]
 edition = "2018"
 
 [dependencies]
-azure_core = { path = "../core", version = "0.1.0" }
-oauth2 = "4.0.0"
+reqwest = { version = "0.11", features = ["json"], default-features = false }
+azure_core = { path = "../core", default-features = false }
+oauth2 = { version = "4.0.0", default-features = false }
 url = "2.2"
 futures = "0.3"
 serde = { version = "1.0", features = ["derive"] }
 chrono = { version = "0.4", features = ["serde"] }
 serde_json = "1.0"
 log = "0.4"
-reqwest = { version = "0.11", features = ["json"] }
 async-timer = "1.0.0-beta.7"
 thiserror = "1.0"
 async-trait = "0.1"
@@ -33,6 +33,8 @@ env_logger = "0.8"
 serde_test = "1"
 
 [features]
-default = ["development"]
+default = ["development", "enable_reqwest"]
+enable_reqwest = ["reqwest/default-tls", "oauth2/native-tls", "azure_core/enable_reqwest"]
+enable_reqwest_rustls = ["reqwest/rustls-tls", "oauth2/rustls-tls", "azure_core/enable_reqwest_rustls"]
 development = []
 test_e2e = []