chore: Add Keybase HasByNameOrAddress, HasByName and HasByAddress

[jefft0]

The Keybase interface has GetByNameOrAddress, GetByName and GetByAddress. If an application simply wants to check if the key is in the key base, it must use one of these and check for an error, as is done in the gnokey command line.

		_, err = kb.GetByName(name)
		if err == nil {
			// account exists, ask for user confirmation
			...
		}

A GnoMobile app also needs to check for the key. But it's expensive to return the entire key info. The byte buffer must be copies multiple times, in the Keybase and in the gRPC interface, and the key info structure must be reformatted to Protobuf and then to the application's language. And not preferable to generate errors to pass information in normal program flow.

In the underlying DB interface, there is already a Has function. This PR updates the Keybase with the related functions HasByNameOrAddress, HasByName and HasByAddress which use Has to inexpensively return a simple bool. It also updates the gnokey command line to use HasByName to be more clear:

		if has, err := kb.HasByName(name); err == nil && has {
			// account exists, ask for user confirmation
			...
		}

[codecov]

Codecov Report

Attention: 36 lines in your changes are missing coverage. Please review.

Comparison is base (199cd29) 47.87% compared to head (2e1b2e7) 55.11%.
Report is 23 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1313      +/-   ##
==========================================
+ Coverage   47.87%   55.11%   +7.24%     
==========================================
  Files         372      421      +49     
  Lines       63019    67456    +4437     
==========================================
+ Hits        30168    37179    +7011     
+ Misses      30384    27369    -3015     
- Partials     2467     2908     +441     

Files	Coverage Δ
tm2/pkg/crypto/keys/types.go	54.43% <ø> (ø)
tm2/pkg/crypto/keys/client/add.go	29.86% <0.00%> (-1.22%)	⬇️
tm2/pkg/crypto/keys/keybase.go	34.79% <0.00%> (-16.10%)	⬇️
tm2/pkg/crypto/keys/lazy_keybase.go	0.00% <0.00%> (ø)

... and 144 files with indirect coverage changes

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[moul]

LGTM, makes sense.