Migrate to Bzlmod.

[SanjayVas]

This updates Bazel to 7.0.1.

[wfa-reviewable]

This change is 

[SanjayVas]

Note that the [warning][perf,memops] Cannot use file /tmp/hsperfdata_user/2 because it is locked by another process (errno = 11) message can be safely ignored. It will be removed once we upgrade to a release of rules_jvm_external that includes bazel-contrib/rules_jvm_external#988

[SanjayVas]

Reviewable status: 0 of 156 files reviewed, all discussions resolved (waiting on @YuhongWang-Amazon)

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src/main/kotlin/org/wfanet/measurement/gcloud/spanner/testing/SpannerEmulator.kt line 87 at r2 (raw file):

        val readyMessage = "Server address: $emulatorHost"

        emulator.errorStream.use { input ->

Spanner emulator made some minor changes to its output

[YuhongWang-Amazon]

Reviewed 102 of 132 files at r1, 52 of 54 files at r2, 2 of 2 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @SanjayVas)