Add an option to make the stac-browser S3 bucket publicly accessible

[emileten]

Recently it became non-trivial to create a publicly accessible S3 bucket with CDK code. Adding this as a boolean option to the stac browser options would be useful for users opting for static s3 website hosting -- it spares them these lines of code in their client :

stac_browser_bucket = s3.Bucket(
    browser_stack,
    "stac-browser-bucket",
    bucket_name=f"{APP_NAME}-{STAGE_NAME}",
    removal_policy=RemovalPolicy.DESTROY,
    auto_delete_objects=True,
    website_index_document="index.html",
    public_read_access=True,
    block_public_access=s3.BlockPublicAccess(
        block_public_acls=False,
        block_public_policy=False,
        ignore_public_acls=False,
        restrict_public_buckets=False,
    ),
    object_ownership=s3.ObjectOwnership.OBJECT_WRITER,
)