Proto commits in sigstore/sigstore-java

These 3 commits are when the Protocol Buffers files have changed:

Commit:7661ff6
Author:Appu Goundan
Committer:Appu Goundan

Use newer required protos for google apis fulcio and protobuf-specs need a small number of protos from googleapis/googleapi but `com.google.api.grpc:proto-google-common-protos` has gone out of date. We can go back to it if they update it. Signed-off-by: Appu Goundan <appu@google.com>

The documentation is generated from this commit.

Commit:bf06a6d
Author:Vladimir Sitnikov
Committer:Vladimir Sitnikov

Move src -> sigstore-java/src Signed-off-by: Vladimir Sitnikov <sitnikov.vladimir@gmail.com>

Commit:eae64e8
Author:Appu Goundan

Add fulcio grpc definition and generation Signed-off-by: Appu Goundan <appu@google.com>