Specify that SetBootConfig cannot specify dynamic config.

[robshakir]

 * (M) bootconfig/bootconfig.proto
  - https://github.com/openconfig/bootz/pull/158 adds support for
    the `BootConfig` message to specify an initial dynamic config
    as either OpenConfig or vendor-proprietary config. This
    is required to allow mutable configuration to be specified at
    initial device bootstrap. It is not valid after this initial
    bootstrap, when `gNMI.Set` manipulates the dynamic config.

    This change explicitly notes that `SetBootConfig`'s payload
    MUST NOT contain these dynamic_* fields, and if they are
    specified an error should be returned.

[coveralls]

Pull Request Test Coverage Report for Build 16208035127

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Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 3210 unchanged lines in 19 files lost coverage.
• Overall coverage remained the same at 0.0%

---

Files with Coverage Reduction	New Missed Lines	%
common/common.pb.go	36	0.0%
bgp/bgp.pb.go	42	0.0%
bootconfig/bootconfig.pb.go	53	0.0%
factory_reset/factory_reset.pb.go	64	0.0%
debug/debug.pb.go	68	0.0%
types/types.pb.go	68	0.0%
layer2/layer2.pb.go	104	0.0%
mpls/mpls.pb.go	125	0.0%
file/file.pb.go	139	0.0%
diag/diag.pb.go	143	0.0%

Totals
Change from base Build 15695000326:	0.0%
Covered Lines:	0
Relevant Lines:	12442

---

💛 - Coveralls

[dplore]

LGTM. Minor suggestion to maybe help clarify what 'bootstrapping' is in OC terms.