fw-rust: Prepare to implement Si5351 commands

Show settings of Si5351 channels on home screen. Initialize I2c and
Si5351.

firmware/rust/Cargo.lock

@@ -55,6 +55,12 @@ dependencies = [
  "rustc_version",
 ]
 
+[[package]]
+name = "bitflags"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
+
 [[package]]
 name = "cfg-if"
 version = "0.1.10"
@@ -70,6 +76,7 @@ dependencies = [
  "embedded-hal",
  "nb 1.0.0",
  "panic-halt",
+ "si5351",
 ]
 
 [[package]]
@@ -157,6 +164,16 @@ version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
 
+[[package]]
+name = "si5351"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c06c1f1f280165963ce5fdff953a5303ac186b2b723aa1ed33916db70ceabfb8"
+dependencies = [
+ "bitflags",
+ "embedded-hal",
+]
+
 [[package]]
 name = "syn"
 version = "1.0.86"