[Crypto] Implement support for high-level crypto APIs

[ItalyPaleAle]

This implements support for the high-level crypto APIs implemented here: dapr/dapr#6197

These allow encrypting and decrypting files of arbitrary length (up to 256TB :) ), while working on a stream of data.

The gRPC APIs are quite complex as they require data to be chunked, but the SDK takes care of all that complexity and offers a simple API with Encrypt and Decrypt. Both accept a readable stream as input (io.Reader) and return a readable stream (io.Reader) that receives the processed data.

Example usage. This reads a file and encrypts it, storing the result in another file:

// Input file, clear-text
rf, err := os.Open("input")
if err != nil {
	panic(err)
}
defer rf.Close()

// Output file, encrypted
wf, err := os.Create("output.enc")
if err != nil {
	panic(err)
}
defer wf.Close()

// Encrypt the data using Dapr
out, err := sdkClient.Encrypt(context.Background(), rf, dapr.EncryptOptions{
	// These are the 3 required parameters
	ComponentName: "mycryptocomponent",
	KeyName:        "mykey",
	Algorithm:     "RSA",
})
if err != nil {
	panic(err)
}

// Read the stream and copy it to the out file
n, err := io.Copy(wf, out)
if err != nil {
	panic(err)
}
fmt.Println("Written", n, "bytes")

Decrypting works very similarly:

out, err := sdkClient.Decrypt(context.Background(), rf, dapr.EncryptOptions{
	// Only required option is the component name
	ComponentName: "mycryptocomponent",
})

[codecov]

Codecov Report

Merging #387 (54d4130) into main (b14253b) will increase coverage by 0.88%.
The diff coverage is 83.75%.

@@            Coverage Diff             @@
##             main     #387      +/-   ##
==========================================
+ Coverage   69.08%   69.97%   +0.88%     
==========================================
  Files          31       33       +2     
  Lines        2491     2651     +160     
==========================================
+ Hits         1721     1855     +134     
- Misses        676      695      +19     
- Partials       94      101       +7     

Impacted Files	Coverage Δ
client/client.go	69.74% <ø> (ø)
client/crypto.go	83.11% <83.11%> (ø)
client/bufpool.go	100.00% <100.00%> (ø)

[yaron2]

@daixiang0 can you please review this?