fix: Initialize rustls's CryptoProvider early in the code

[BulkBeing]

The rustls crate is used to generate SSL certs for metrics server of the monovertex. The metrics server handles /metrics and all the k8s health check endpoints (/livez, /readyz and /sidecar-livez). Since the CryptoProvider was not initialized, rustls was crashing:

2025-01-08T07:00:47.475519Z  INFO numaflow_core::source: Started streaming source with batch size: 500
thread 'tokio-runtime-worker' panicked at /usr/local/cargo/registry/src/index.crates.io-6f17d22bba15001f/rustls-0.23.19/src/crypto/mod.rs:249:14:
no process-level CryptoProvider available -- call CryptoProvider::install_default() before this point
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
thread 'tokio-runtime-worker' panicked at /usr/local/cargo/registry/src/index.crates.io-6f17d22bba15001f/axum-server-0.7.1/src/tls_rustls/mod.rs:192:14:
called `Result::unwrap()` on an `Err` value: JoinError::Panic(Id(43), "no process-level CryptoProvider available -- call CryptoProvider::install_default() before this point", ...)

We were initializing it in specific paths (eg. serving also generates self-signed certs). I'm moving it to the main.rs in this PR.
Verified by running https://github.com/numaproj/numaflow/blob/main/test/monovertex-e2e/testdata/mono-vertex-with-transformer.yaml and https://github.com/numaproj/numaflow/blob/main/examples/21-simple-mono-vertex.yaml.

[codecov]

Codecov Report

Attention: Patch coverage is 40.00000% with 6 lines in your changes missing coverage. Please review.

Project coverage is 67.09%. Comparing base (5f5af1b) to head (0bcf35d).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
rust/numaflow/src/main.rs	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2312      +/-   ##
==========================================
- Coverage   67.12%   67.09%   -0.03%     
==========================================
  Files         351      351              
  Lines       45275    45273       -2     
==========================================
- Hits        30391    30377      -14     
- Misses      13817    13829      +12     
  Partials     1067     1067              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.