feat: enable no_std support for pbjson (#158)

Closes: #156

Addresses the `no_std` compatibility issue with `serde` feature in `ibc-rs`. This is caused by the recent implementation of ProtoJSON serialization and deserialization [0] for the `ics23` Protobuf definitions using `pbjson`, and then re-exporting the ics23 type [1] in `ibc-proto-rs`. Some of our users by then (starting from IBC-rs v0.41.0) are experiencing compilation errors. [2]

To meet this immediate need [3] and the lack of activity in the `pbjson` crate for months, we have taken the initiative to feature `no_std` support in the `informalsystems-pbjson` crate and have it published.

[0] #146
[1] cosmos/ibc-proto-rs#92
[2] informalsystems/ibc-rs#741
[3] cosmos/ibc-proto-rs#98 (comment)

---

* feat: enable no_std support for pbjson

* fix: get serde feature work with no-std

* deps: use informalsystems-pbjson v0.6.0

* deps: use informalsystems-pbjson v0.6.0

Author: Farhad-Shabani

rust/Cargo.toml

@@ -22,7 +22,7 @@ ripemd = {version = "0.1.1", optional = true, default-features = false}
 sha2 = {version = "0.10.2", optional = true, default-features = false}
 sha3 = {version = "0.10.2", optional = true, default-features = false}
 serde = {version = "1.0", optional = true, default-features = false}
-pbjson = {version = "0.5.1", optional = true}
+informalsystems-pbjson = { version = "0.6.0", optional = true, default-features = false }
 
 [dev-dependencies]
 ripemd = {version = "0.1.1"}
@@ -32,10 +32,10 @@ sha2 = {version = "0.10.2"}
 sha3 = {version = "0.10.2"}
 
 [features]
-default = ["std", "host-functions", "serde"]
+default = ["std", "host-functions"]
 
-std = ["prost/std", "bytes/std", "hex/std", "anyhow/std"]
+std = ["prost/std", "bytes/std", "hex/std", "anyhow/std", "informalsystems-pbjson/std", "serde/std"]
 
 host-functions = ["sha2", "sha3", "ripemd"]
 
-serde = ["serde/std", "dep:pbjson"]
+serde = ["dep:serde", "informalsystems-pbjson"]

rust/codegen/Cargo.toml

@@ -10,4 +10,4 @@ edition = "2018"
 bytes = "1.0.1"
 prost = "0.11"
 prost-build = "0.11"
-pbjson-build = "0.5.1"
+informalsystems-pbjson-build = "0.6.0"