Add support for certificates hot reload

[willyborankin]

Description

Added support for certificates hot reload

Issues Resolved

#4427

Check List

• New functionality includes testing
• New functionality has been documented
• New Roles/Permissions have a corresponding security dashboards plugin PR
• API changes companion pull request created
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[codecov]

Codecov Report

Attention: Patch coverage is 74.35897% with 10 lines in your changes missing coverage. Please review.

Project coverage is 71.42%. Comparing base (9b67d54) to head (b1f826c).
Report is 12 commits behind head on main.

Files with missing lines	Patch %	Lines
...rg/opensearch/security/ssl/SslSettingsManager.java	79.31%	6 Missing ⚠️
.../opensearch/security/OpenSearchSecurityPlugin.java	33.33%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4880      +/-   ##
==========================================
- Coverage   71.45%   71.42%   -0.03%     
==========================================
  Files         334      334              
  Lines       22509    22543      +34     
  Branches     3582     3586       +4     
==========================================
+ Hits        16084    16102      +18     
- Misses       4633     4645      +12     
- Partials     1792     1796       +4     

Files with missing lines	Coverage Δ
...org/opensearch/security/ssl/SslContextHandler.java	98.87% <100.00%> (+0.03%)	⬆️
...g/opensearch/security/support/ConfigConstants.java	95.23% <ø> (ø)
.../opensearch/security/OpenSearchSecurityPlugin.java	83.56% <33.33%> (-0.45%)	⬇️
...rg/opensearch/security/ssl/SslSettingsManager.java	71.59% <79.31%> (-0.41%)	⬇️

... and 5 files with indirect coverage changes

---- 🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests
• JS Bundle Analysis - Avoid shipping oversized bundles

[cwperks]

@willyborankin Can you open a documentation PR for this as well since this adds a new setting?

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/security/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/security/backport-2.x
# Create a new branch
git switch --create backport/backport-4880-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 c22002a5313fa2cc265b43c2177ecc2357ad0701
# Push it to GitHub
git push --set-upstream origin backport/backport-4880-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/security/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-4880-to-2.x.