Add support for PGP encryption/decryption with files

[TharmiganK]

Purpose

$Subject

Fixes: https://github.com/ballerina-platform/ballerina-library/issues/7064

With this PR, two new functionalities are added to the crypto module:

• encryptPgpAsFile: Read the content from a file, encrypt with PGP and write the encrypted file in the output path
• decryptPgpAsFile: Read the content from an PGP encrypted file, decrypt with PGP and write the decrypted file in the output path

With this new APIs, large files can be encrypted/decrypted with PGP, without loading the entire content into the memory.

Find the following results with large files(the files are generated by empty characters):

File Size	Encryption duration	Encryption max memory usage	Decryption(from the encrypted file) duration	Decryption max memory usage
1 GB	7.23 seconds	46 MB	4.22 seconds	46 MB
5 GB	38.13 seconds	57 MB	20 seconds	46 MB

Examples

• Encryption sample:

check crypto:encryptPgpAsFile(inputPath, publicKeyPath, outputPath);

• Decryption sample:

check crypto:decryptPgpAsFile(inputFilePath, privateKeyPath, passPhraseInBytes, outputFilePath);

Checklist

• [x] Linked to an issue
• [x] Updated the changelog
• [x] Added tests
• [x] Updated the spec
• [x] Checked native-image compatibility