Load entities and policies from json file

[cleissonbarbosa]

Reason: Unable to load a large amount of entities (30,000 - 4.5MB) from the /data endpoint

What PR does: Adds the possibility to load entities and policies from a json file at rocket startup

Use the -d or --data option and inform the path of the json file you want to load in cedar's memory, it is also possible to use a DATA environment variable

examples:

cargo run -- -d "./examples/data.json"

cargo run -- --data="./examples/data.json"

export DATA="./examples/data.json"
cargo run

---

Use the --policies option and inform the path of the json file you want to load in cedar's memory, it is also possible to use a POLICIES environment variable

examples:

cargo run -- --policies="./examples/policies.json"

export POLICIES="./examples/policies.json"
cargo run

[cleissonbarbosa]

@omer9564 Thank you very much for the review, in addition to the changes you requested, I changed the word policy to policies in the config.

[cleissonbarbosa]

two suggestion comments ( might make the code simpler ) one missing new line again 😅 , Besides that it looks great 💪

😅 thank you very much for the suggestion.

[orweis]

@cleissonbarbosa - I love what I'm seeing here - Kudos. @danielbass37 can we make sure @cleissonbarbosa gets some swag, in show of appreciation for his OSS contribution here.

[danielbass37]

@cleissonbarbosa PMed you in the community <3

[cleissonbarbosa]

@orweis @danielbass37 Thank you guys 💜