Add import, export and delete instance methods.

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Here's the log from Synthtool:

synthtool > Executing /tmpfs/src/git/autosynth/working_repo/Redis/synth.py.
synthtool > Ensuring dependencies.
synthtool > Pulling artman image.
latest: Pulling from googleapis/artman
Digest: sha256:846102ebf7ea2239162deea69f64940443b4147f7c2e68d64b332416f74211ba
Status: Image is up to date for googleapis/artman:latest
synthtool > Cloning googleapis.
synthtool > Running generator for google/cloud/redis/artman_redis_v1beta1.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/php/google-cloud-redis-v1beta1.
synthtool > Running generator for google/cloud/redis/artman_redis_v1.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/php/google-cloud-redis-v1.
synthtool > Replaced 'Copyright \\d{4}' in src/V1/Gapic/CloudRedisGapicClient.php.
synthtool > Replaced 'Copyright \\d{4}' in src/V1beta1/Gapic/CloudRedisGapicClient.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/System/V1/CloudRedisClientTest.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/System/V1beta1/CloudRedisClientTest.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/Unit/V1/CloudRedisClientPartialVeneerTest.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/Unit/V1/CloudRedisClientTest.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/Unit/V1beta1/CloudRedisClientPartialVeneerTest.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/Unit/V1beta1/CloudRedisClientTest.php.
synthtool > Replaced 'will be removed in the next major release' in src/V1/Instance_Tier.php.
synthtool > Replaced 'will be removed in the next major release' in src/V1/Instance_State.php.
synthtool > Replaced 'will be removed in the next major release' in src/V1/FailoverInstanceRequest_DataProtectionMode.php.
synthtool > Replaced 'will be removed in the next major release' in src/V1beta1/Instance_Tier.php.
synthtool > Replaced 'will be removed in the next major release' in src/V1beta1/Instance_State.php.
synthtool > Replaced 'will be removed in the next major release' in src/V1beta1/FailoverInstanceRequest_DataProtectionMode.php.
synthtool > No replacements made in src/**/Gapic/CloudRedisGapicClient.php for pattern Instance_Tier, maybe replacement is not longer needed?
synthtool > Cleaned up 1 temporary directories.
synthtool > Wrote metadata to synth.metadata.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@bb0a0b3). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #2011   +/-   ##
=========================================
  Coverage          ?   92.56%           
  Complexity        ?     4374           
=========================================
  Files             ?      303           
  Lines             ?    12996           
  Branches          ?        0           
=========================================
  Hits              ?    12030           
  Misses            ?      966           
  Partials          ?        0

---

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Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[codecov]

Codecov Report

Merging #2011 into master will increase coverage by <.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #2011      +/-   ##
============================================
+ Coverage     92.56%   92.57%   +<.01%     
- Complexity     4374     4378       +4     
============================================
  Files           303      304       +1     
  Lines         12996    13012      +16     
============================================
+ Hits          12030    12046      +16     
  Misses          966      966

Impacted Files	Coverage Δ	Complexity Δ
Datastore/src/Connection/Grpc.php	98.08% <0%> (ø)	48% <0%> (ø)	⬇️
Core/src/Compute/Metadata/Readers/StreamReader.php	100% <0%> (ø)	2% <0%> (ø)	⬇️
Core/src/Compute/Metadata.php	100% <0%> (ø)	10% <0%> (+1%)	⬆️
...src/Compute/Metadata/Readers/HttpHandlerReader.php	100% <0%> (ø)	3% <0%> (?)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update bb0a0b3...66c6586. Read the comment docs.

[googlebot]

So there's good news and bad news.

👍 The good news is that everyone that needs to sign a CLA (the pull request submitter and all commit authors) have done so. Everything is all good there.

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[googlebot]

A Googler has manually verified that the CLAs look good.

(Googler, please make sure the reason for overriding the CLA status is clearly documented in these comments.)

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