Disable default features for rocksdb

[tcharding]

Description

In an effort to reduce the build times of rocksdb we can set
default-features to false.

Please note, the build speed up is minimil

With default features:

cargo check --features compact_filters  890.91s user 47.62s system 352% cpu 4:26.55 total

Without default features:

cargo check --features compact_filters  827.07s user 47.63s system 352% cpu 4:08.39 total

Enable snappy since it seems like this is the current default compression
algorithm, therefore this patch (hopefully) makes no changes to the usage of the
rocksdb library in bdk. From the rocksdb code:

    /// Sets the compression algorithm that will be used for compressing blocks.
    ///
    /// Default: `DBCompressionType::Snappy` (`DBCompressionType::None` if
    /// snappy feature is not enabled).
    ///
    /// # Examples
    ///
    /// ```
    /// use rocksdb::{Options, DBCompressionType};
    ///
    /// let mut opts = Options::default();
    /// opts.set_compression_type(DBCompressionType::Snappy);
    /// ```
    pub fn set_compression_type(&mut self, t: DBCompressionType) {
        ....

Notes to the reviewers

Done in an attempt to help with #244

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing

New Features:

• I've added tests for the new feature
• I've added docs for the new feature
• I've updated CHANGELOG.md

Bugfixes:

• This pull request breaks the existing API
• I've added tests to reproduce the issue which are now passing
• I'm linking the issue being fixed by this PR

[RCasatta]

LGTM

for rocksdb:
default = ["snappy", "lz4", "zstd", "zlib", "bzip2"]
it appears we don't need the other compression algorithms

[tcharding]

LGTM

for rocksdb:
default = ["snappy", "lz4", "zstd", "zlib", "bzip2"]
it appears we don't need the other compression algorithms

That was my guess also, I have zero experience with rocksdb. At first I tried to build with no features enabled and that builds just fine but from the docs I posted above I'm guessing that this means no compression which I guess we don't want.

Thanks for the review!

[afilini]

I think this needs a rebase before we can merge it, because in master there are now two more CI jobs